I am building an SNMP Agent for a Windows application using the Microsoft WinSNMP API. Currently everything is working for single-item get and set-request, and also for get-next to allow walking the defined tree (albeit with some caveats that are not relevant to this question).
I am now looking at multi-item get and also get-bulk.
My current procedure is to iterate through the list of requested items (the varbindlist within the PDU), treating each one individually, effectively causing an internal get. The result is added to the VBL, set into the PDU, and then sent back to the SNMP Manager, taking into account invalid requests, etc.
My question is how should I handle "too much" data (data that cannot fit into a single transport layer message)? Or more accurately, is there a way to test whether data is "too big" without actually attempting to transmit? The only way I can see in the API is to try sending, check the error, and try again.
In the case of a get-request this isn't a problem - if you can't return all of the requested data, you fail: so attempt sending, and if the error report is SNMPAPI_TL_PDU_TOO_BIG, send a default "error" PDU.
However, it is allowable for a response to bulk-get to return partial results.
The only way I can see to handle this is a tedious (?) loop of removing an item and trying again. Something similar to the following (some detail removed for brevity):
// Create an empty varbindlist
vbl = SnmpCreateVbl(session, NULL, NULL);
// Add all items to the list
SnmpSetVb(vbl, &oid, &value); // for each OID/Value pair
// Create the PDU
pdu = SnmpCreatePdu(session, SNMP_PDU_RESPONSE, ..., vbl);
bool retry;
do {
retry = false;
smiINT failed = SnmpSendMsg(session, ..., pdu);
if (failed && SNMPAPI_TL_PDU_TOO_BIG == SnmpGetLastError()) {
// too much data, delete the last vb
SnmpDeleteVb(vbl, SnmpCountVbl(vbl));
SnmpSetPduData(pdu, ..., vbl);
retry = true;
};
} while(retry);
This doesn't seem like an optimal approach - so is there another way that I've missed?
As a side-note, I know about libraries such as net-snmp, but my question is specific to the Microsoft API.
The RFC does require you to do what you pasted,
https://www.rfc-editor.org/rfc/rfc3416
Read page 16.
There does not seem to be a function exposed by WinSNMP API that can do this for you, so you have to write your own logic to handle it.
Related
The Q&A is currently a subject of meta discussion, do participate. The current plan is to split where possible into Q&As. Answers to the A&A are community wiki and the question should become one when the status is resolved.
Preface
This Q&A strives to become a collection and a reference target for common errors encountered during development in Google Apps Script language in hopes to improve long-term maintainability of google-apps-script tag.
There are several similar and successful undergoings in other languages and general-purpose tags (see c++, android, php, php again), and this one follows suit.
Why it exists?
The amount of questions from both new and experienced developers regarding the meaning and solutions to errors encountered during development and production that can be effectively reduced to a single answer is substantial. At the time of writing, even running a query only by language tag yields:
"Cannot find method" 8 pages
"Cannot read property" 9 pages
"Cannot call ... in this context" 5 pages
"You do not have permission" 11 pages
Linking to a most relevant duplicate is hard and time-consuming for volunteers due to the need to consider nuances and often poorly-worded titles.
What it consists of?
Entries in this Q&A contain are designed to provide info on how to:
parse the error message structure
understand what the error entails
consistently reproduce (where applicable)
resolve the issue
provide a link to canonical Q&A (where possible)
Table of Contents
To help you navigate the growing reference please use the TOC below:
General errors
Service-specific errors
What this is not?
The scope of the Q&A is limited to common (not trivial). This is not:
a catch-all guide or "best practices" collection
a reference for general ECMAScript errors
GAS documentation
a resources list (we have a tag wiki for that)
What to add?
When adding an entry, please, consider the following:
is the error common enough (see "why" section for examples)?
can the solution be described concisely and be applicable for most cases?
Preface
The answer provides a guide on general errors that can be encountered when working with any Google service (both built-in and advanced) or API. For errors specific to certain services, see the other answer.
Back to reference
General errors
Message
TypeError: Cannot read property 'property name here' from undefined (or null)
Description
The error message indicates that you are trying to access a property on an Object instance, but during runtime the value actually held by a variable is a special data type undefined. Typically, the error occurs when accessing nested properties of an object.
A variation of this error with a numeric value in place of property name indicates that an instance of Array was expected. As arrays in JavaScript are objects, everything mentioned here is true about them as well.
There is a special case of dynamically constructed objects such as event objects that are only available in specific contexts like making an HTTP request to the app or invoking a function via time or event-based trigger.
The error is a TypeError because an "object" is expected, but "undefined" is received
How to fix
Using default values
Logical OR || operator in JavaScript has an intersting property of evaluating the right-hand side iff the left-hand is falsy. Since objects in JS are truthy, and undefined and null are falsy, an expression like (myVar || {}).myProp [(myVar || [])[index] for arrays] will guarantee that no error is thrown and the property is at least undefined.
One can also provide default values: (myVar || { myProp : 2 }) guarantees accessing myProp to return 2 by default. Same goes for arrays: (myVar || [1,2,3]).
Checking for type
Especially true for the special case, typeof operator combined with an if statement and a comparison operator will either allow a function to run outside of its designated context (i.e. for debugging purposes) or introduce branching logic depending on whether the object is present or not.
One can control how strict the check should be:
lax ("not undefined"): if(typeof myVar !== "undefined") { //do something; }
strict ("proper objects only"): if(typeof myVar === "object" && myVar) { //do stuff }
Related Q&As
Parsing order of the GAS project as the source of the issue
Message
Cannot convert some value to data type
Description
The error is thrown due to passing an argument of different type than a method expects. A common mistake that causes the error is accidental coercion of a number to string.
How to reproduce
function testConversionError() {
const ss = SpreadsheetApp.getActiveSheet();
ss.getRange("42.0",1);
}
How to fix
Make sure that the value referenced in the error message is of data type required by documentation and convert as needed.
Message
Cannot call Service and method name from this context
Description
This error happens on a context mismatch and is specific to container-bound scripts.
The primary use case that results in the error is trying to call a method only available in one document type (usually, getUi() as it is shared by several services) from another (i.e. DocumentApp.getUi() from a spreadsheet).
A secondary, but also prominent case is a result of calling a service not explicitly allowed to be called from a custom function (usually a function marked by special JSDoc-style comment #customfunction and used as a formula).
How to reproduce
For bound script context mismatch, declare and run this function in a script project tied to Google Sheets (or anything other than Google Docs):
function testContextMismatch() {
const doc = DocumentApp.getUi();
}
Note that calling a DocumentApp.getActiveDocument() will simply result in null on mismatch, and the execution will succeed.
For custom functions, use the function declared below in any cell as a formula:
/**
* #customfunction
*/
function testConversionError() {
const ui = SpreadsheetApp.getUi();
ui.alert(`UI is out of scope of custom function`);
}
How to fix
Context mismatch is easily fixed by changing the service on which the method is called.
Custom functions cannot be made to call these services, use custom menus or dialogs.
Message
Cannot find method Method name here
The parameters param names do not match the method signature for method name
Description
This error has a notoriously confusing message for newcomers. What it says is that a type mismatch occurred in one or more of the arguments passed when the method in question was called.
There is no method with the signature that corresponds to how you called it, hence "not found"
How to fix
The only fix here is to read the documentation carefully and check if order and inferred type of parameters are correct (using a good IDE with autocomplete will help). Sometimes, though, the issue happens because one expects the value to be of a certain type while at runtime it is of another. There are several tips for preventing such issues:
Setting up type guards (typeof myVar === "string" and similar).
Adding a validator to fix the type dynamically thanks to JavaScript being dynamically typed.
Sample
/**
* #summary pure arg validator boilerplate
* #param {function (any) : any}
* #param {...any} args
* #returns {any[]}
*/
const validate = (guard, ...args) => args.map(guard);
const functionWithValidator = (...args) => {
const guard = (arg) => typeof arg !== "number" ? parseInt(arg) : arg;
const [a,b,c] = validate(guard, ...args);
const asObject = { a, b, c };
console.log(asObject);
return asObject;
};
//driver IIFE
(() => {
functionWithValidator("1 apple",2,"0x5");
})()
Messages
You do not have permission to perform that action
The script does not have permission to perform that action
Description
The error indicates that one of the APIs or services accessed lacks sufficient permissions from the user. Every service method that has an authorization section in its documentation requires at least one of the scopes to be authorized.
As GAS essentially wraps around Google APIs for development convenience, most of the scopes listed in OAuth 2.0 scopes for APIs reference can be used, although if one is listed in the corresponding docs it may be better to use it as there are some inconsistencies.
Note that custom functions run without authorization. Calling a function from a Google sheet cell is the most common cause of this error.
How to fix
If a function calling the service is ran from the script editor, you are automatically prompted to authorize it with relevant scopes. Albeit useful for quick manual tests, it is best practice to set scopes explicitly in application manifest (appscript.json). Besides, automatic scopes are usually too broad to pass the review if one intends to publish the app.
The field oauthScopes in manifest file (View -> Show manifest file if in code editor) should look something like this:
"oauthScopes": [
"https://www.googleapis.com/auth/script.container.ui",
"https://www.googleapis.com/auth/userinfo.email",
//etc
]
For custom functions, you can fix it by switching to calling the function from a menu or a button as custom functions cannot be authorized.
For those developing editor Add-ons, this error means an unhandled authorization lifecycle mode: one has to abort before calls to services that require authorization in case auth mode is AuthMode.NONE.
Related causes and solutions
#OnlyCurrentDoc limiting script access scope
Scopes autodetection
Message
ReferenceError: service name is not defined
Description
The most common cause is using an advanced service without enabling it. When such a service is enabled, a variable under the specified identifier is attached to global scope that the developer can reference directly. Thus, when a disabled service is referenced, a ReferenceError is thrown.
How to fix
Go to "Resources -> Advanced Google Services" menu and enable the service referenced. Note that the identifier should equal the global variable referenced.
For a more detailed explanation, read the official guide.
If one hasn't referenced any advanced services then the error points to an undeclared variable being referenced.
Message
The script completed but did not return anything.
Script function not found: doGet or doPost
Description
This is not an error per se (as the HTTP response code returned is 200 and the execution is marked as successful, but is commonly regarded as one. The message appears when trying to make a request/access from browser a script deployed as a Web App.
There are two primary reasons why this would happen:
There is no doGet or doPost trigger function
Triggers above do not return an HtmlOutput or TextOutput instance
How to fix
For the first reason, simply provide a doGet or doPost trigger (or both) function. For the second, make sure that all routes of your app end with creation of TextOutput or HtmlOutput:
//doGet returning HTML
function doGet(e) {
return HtmlService.createHtmlOutput("<p>Some text</p>");
}
//doPost returning text
function doPost(e) {
const { parameters } = e;
const echoed = JSON.stringify(parameters);
return ContentService.createTextOutput(echoed);
}
Note that there should be only one trigger function declared - treat them as entry points to your application.
If the trigger relies on parameter / parameters to route responses, make sure that the request URL is structured as "baseURL/exec?query" or "baseURL/dev?query" where query contains parameters to pass.
Related Q&As
Redeploying after declaring triggers
Message
We're sorry, a server error occurred. Please wait a bit and try again.
Description
This one is the most cryptic error and can occur at any point with nearly any service (although DriveApp usage is particularly susceptible to it). The error usually indicates a problem on Google's side that either goes away in a couple of hours/days or gets fixed in the process.
How to fix
There is no silver bullet for that one and usually, there is nothing you can do apart from filing an issue on the issue tracker or contacting support if you have a GSuite account. Before doing that one can try the following common remedies:
For bound scripts - creating a new document and copying over the existing project and data.
Switch to using an advanced Drive service (always remember to enable it first).
There might be a problem with a regular expression if the error points to a line with one.
Don't bash your head against this error - try locating affected code, file or star an issue and move on
Syntax error without apparent issues
This error is likely to be caused by using an ES6 syntax (for example, arrow functions) while using the deprecated Rhino runtime (at the time of writing the GAS platform uses V8).
How to fix
Open "appscript.json" manifest file and check if runtimeVersion is set to "V8", change it if not, or remove any ES6 features otherwise.
Quota-related errors
There are several errors related to quotas imposed on service usage. Google has a comprehensive list of those, but as a general rule of thumb, if a message matches "too many" pattern, you are likely to have exceeded the respective quota.
Most likely errors encountered:
Service invoked too many times: service name
There are too many scripts running
Service using too much computer time for one day
This script has too many triggers
How to fix
In most cases, the only fix is to wait until the quota is refreshed or switch to another account (unless the script is deployed as a Web App with permission to "run as me", in which case owner's quotas will be shared across all users).
To quote documentation at the time:
Daily quotas are refreshed at the end of a 24-hour window; the exact time of this refresh, however, varies between users.
Note that some services such as MailApp have methods like getRemainingDailyQuota that can check the remaining quota.
In the case of exceeding the maximum number of triggers one can check how many are installed via getProjectTriggers() (or check "My triggers" tab) and act accordingly to reduce the number (for example, by using deleteTrigger(trigger) to get rid of some).
Related canonical Q&As
How are daily limitations being applied and refreshed?
"Maximum execution time exceeded" problem
Optimizing service calls to reduce execution time
References
How to make error messages more meaningful
Debugging custom functions
Service-specific errors
The answer concerns built-in service-related errors. For general reference see the other answer. Entries addressing issues with services listed in official reference are welcome.
Back to reference
SpreadsheetApp
The number of rows in the range must be at least 1
This error is usually caused by calling the getRange method where the parameter that sets the number of rows happens to equal to 0. Be careful if you depend on getLastRow() call return value - only use it on non-empty sheets (getDataRange will be safer).
How to reproduce
sh.getRange(1, 1, 0, sh.getLastColumn()); //third param is the number of rows
How to fix
Adding a guard that prevents the value from ever becoming 0 should suffice. The pattern below defaults to the last row with data (optional if you only need a certain number of rows) and to 1 if that also fails:
//willFail is defined elsewhere
sh.getRange(1, 1, willFail || sh.getLastRow() || 1, sh.getLastColumn());
Error: “Reference does not exist”
The error happens when calling a custom function in a spreadsheet cell that does not return a value. The docs do mention only that one "must return a value to display", but the catch here is that an empty array is also not a valid return value (no elements to display).
How to reproduce
Call the custom function below in any Google Sheets spreadsheet cell:
/**
* #customfunction
*/
const testReferenceError = () => [];
How to fix
No specific handling is required, just make sure that length > 0.
The number of rows or cells in the data does not match the number of rows or cells in the range. The data has N but the range has M.
Description
The error points to a mismatch in dimensions of range in relation to values. Usually, the issue arises when using setValues() method when the matrix of values is smaller or bigger than the range.
How to reproduce
function testOutOfRange() {
const ss = SpreadsheetApp.getActiveSpreadsheet();
const sh = ss.getActiveSheet();
const rng = sh.getActiveRange();
const vals = rng.getValues();
try {
vals.push([]);
rng.setValues(vals);
} catch (error) {
const ui = SpreadsheetApp.getUi();
ui.alert(error.message);
}
}
How to fix
If it is routinely expected for values to get out of bounds, implement a guard that catches such states, for example:
const checkBounds = (rng, values) => {
const targetRows = rng.getHeight();
const targetCols = rng.getWidth();
const { length } = values;
const [firstRow] = values;
return length === targetRows &&
firstRow.length === targetCols;
};
The coordinates of the range are outside the dimensions of the sheet.
Description
The error is a result of a collision between two issues:
The Range is out of bounds (getRange() does not throw on requesting a non-existent range)
Trying to call a method on a Range instance referring to a non-existent dimension of the sheet.
How to reproduce
function testOB() {
const ss = SpreadsheetApp.getActiveSpreadsheet();
const sh = ss.getActiveSheet();
const rng = sh.getRange(sh.getMaxRows() + 1, 1);
rng.insertCheckboxes();
}
How to fix
Check that number of rows (getMaxRow()) and columns (getMaxColumns()) are both greater or equal to the parameters passed to getRange() method call and change them accordingly.
Exception: You can't create a filter in a sheet that already has a filter.
Description
The message means that you are trying to call a createFilter method on a Range in a Sheet that already has a filter set (either via UI or script), thus violating the restriction on 1 filter per Sheet, to quote the documentation:
There can be at most one filter in a sheet.
How to reproduce
const testFilterExistsError = () => {
const sh = SpreadsheetApp.getActiveSheet();
const rng = sh.getDataRange();
const filter1 = rng.createFilter();
const filter2 = rng.createFilter();
};
How to fix
Add a guard that checks for the existence of the filter first. getFilter returns either a filter or null if called on a Range instance and is perfect for the job:
const testFilterGuard = () => {
const sh = SpreadsheetApp.getActiveSheet();
const rng = sh.getDataRange();
const filter = rng.getFilter() || rng.createFilter();
//do something useful;
};
UrlFetchApp
Attribute provided with no value: url
Description
The error is specific to UrlFetchApp service and happens when fetch or fetchAll method gets called with an empty string or non-string value.
How to reproduce
const response = UrlFetchApp.fetch("", {});
How to fix
Make sure that a string containing a URI (not necessarily valid) is passed to the method as its first argument. As its common root cause is accessing a non-existent property on an object or array, check whether your accessors return an actual value.
I have a SecTrustRef object from the system that I'd like to evaluate myself. Just calling SecTrustEvaluateAsync will be sufficient for this job. The problem is, I must evaluate it in a different process as only this other process has access to the keychains where the CA certificates are stored that may cause evaluation to succeed.
The two processes have an IPC link that allows me to exchange arbitrary byte data between them but I don't see any way to easily serialize a SecTrustRef into byte data and deserialize that data back to an object at the other process. There doesn't seem to be a persistent storage mechanism for SecTrustRef.
So am I overlooking something important here, or do I really have to get all the certs (SecTrustGetCertificateAtIndex) and all the policies (SecTrustCopyPolicies) and serialize these myself?
And if so, how would I serialize a policy?
For the certificate (SecCertificateRef) it's rather easy, I just call SecCertificateCopyData and later on SecCertificateCreateWithData.
But for policies I can only call SecPolicyCopyProperties on one side and later on SecPolicyCreateWithProperties, however the later one requires a 2nd parameter, a policyIdentifier and I see no way to get that value from an existing policy. What am I missing?
Reading through the source of the Security framework, I finally figured it out how to copy a SecPolicyRef:
SecPolicyCreateWithProperties wants what it calls a "policyIdentifier". It's a constant like kSecPolicyAppleIPsec.
This does not get stored directly by the function, it's comparing the value and calling dedicated internal "initializers" (like SecPolicyCreateIPsec).
These in turn call SecPolicyCreate (which is private). They end up passing the same identifier value that you passed to SecPolicyCreateWithProperties.
And this value then gets stored as-is in the _oid field!
The identifier is actually the OID. You can get it either via SecPolicyCopyProperties(policy) (stored in the dictionary with key kSecPolicyOid) or via SecPolicyGetOID (but that returns it as an inconvenient CSSM_OID). Some of those specialized initializers also use values from the properties dictionary passed to SecPolicyCreateWithProperties, those should be present in the copied properties dictionary already.
So this gives us:
Serialization:
CFDictionaryRef createSerializedPolicy(SecPolicyRef policy) {
// Already contains all the information needed.
return SecPolicyCopyProperties(policy);
}
Deserialization:
SecPolicyRef createDeserializedPolicy (CFDictionaryRef serialized) {
CFStringRef oid = CFDictionaryGetValue(serialized, kSecPolicyOid);
if (oid == NULL || CFGetTypeID(oid) != CFStringGetTypeID()) {
return NULL;
}
return SecPolicyCreateWithProperties(oid, serialized);
}
To reproduce the original SecTrustRef as closely as possible, the anchors need to be copied as well. There is an internal variable _anchorsOnly which is set to true once you set anchors. Unfortunately, there is no way to query this value and I've seen it being false in trusts passed by NSURLSession, for example. No idea yet on how to get this value in a public way.
Another problematic bit are the exceptions: if _exceptions is NULL but you query them via SecTrustCopyExceptions(trust), you do get data! And if you assign that to the deserialized trust via SecTrustSetExceptions(trust, exceptions) you suddenly end up with exceptions that were not there before and can change the evaluation result! (I've seen those suddenly appearing exceptions lead to an evaluation result of "proceed" instead of "recoverable trust failure").
I'm trying to get some data from Application.Current.Properties storage. Unfortunately, any time I want to use this Dictionary, I see this error:
An exception of type 'System.AggregateException' occurred in mscorlib.ni.dll but was not handled in user code
Additional information: One or more errors occurred.
And in details I found this:
{"Error in line 1 position 206. Element 'http://schemas.microsoft.com/2003/10/Serialization/Arrays:Value' contains data of the 'http://schemas.microsoft.com/2003/10/Serialization/Arrays:ArrayOfstring' data contract. The deserializer has no knowledge of any type that maps to this contract. Add the type corresponding to 'ArrayOfstring' to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding it to the list of known types passed to DataContractSerializer."}
It seems like I tried to save some non-string data to Application.Current.Properties. Unfortunately I can't run .Clear() method to erease all data, bacause I receive this error any time I'm trying to access this property.
What should I do to make it work?
Well, as its name suggests AggregateException, is just a container for one or more exceptions which may be thrown when using PLINQ or TPL.
As such exceptions may be thrown on different threads and may also occur concurrently, the system automatically catches and rethrows them within an AggregateException wrapper to ensure that they all get reported in one place. The exceptions themselves are exposed via the InnerExceptions property.
You can catch an AggregateException and check which exceptions it actually contains with code such as the following:
try
{
// perform some parallel operation
}
catch (AggregateException aex)
{
string messages = "";
foreach(Exception ex in aex.InnerExceptions)
{
messages += ex.Message + "\r\n";
}
MessageBox.Show(messages);
}
So I suggest you do this to see what is causing the problem
Please, remove your app from your device, Settings - Applications- Uninstall, this works for me. The Auth Object was crash in debug mode.Clean and Rebuild can be Helpfull to.
Using WMQ7.0 with WMB 6.1
I have one flow where I am transforming a message and using MQRFH2.usr for holding some data.
But, I am facing the issue where the MQRFH2.usr is coming in the main message body.
I have deployed the same code in different environments, but I am getting this issue only in one environment.
So, it doesn't seems to be a code issue. It has something to do with configurations.
Kindly, suggest what could be the possible cause.
Check the queue's PROPCTL setting. If this is set to NONE then the behavior is as follows:
If the application does not create a message handle, all the message
properties are removed from the MQRFH2. Name/value pairs in the MQRFH2
headers are left in the message.
Be sure to read the doc page through a couple of times and maybe test with different settings to understand fully how PROPCTL modifies the message content your app receives.
The MQRFH2 headers, if present, always come in the payload part of the message (that's the way webpshere organizes it). You can receive one or more MQRFH2 headers (structures).
Perhaps you are expecting only one and are receiving two? This would explain your message data being left with gibberish.
I use the following code to handler these heards upon receiving a message
MQRFH2 header = null;
// Find and store message length
int msglen = replyMessage.getMessageLength();
MQHeaderList list = new MQHeaderList(replyMessage);
int indexOf = list.indexOf("MQRFH2");
if (indexOf >= 0) {
header = (MQRFH2) list.get(indexOf);
msglen = msglen - header.size();
}
String msgText = replyMessage.readStringOfCharLength(msglen);
Hope it helps.
Martins
Been playing around with Uploadify v3 for few days now and just came to realize some of the codes have been rewritten, for example, onError is no longer existed, I am assuming it's been replaced by onUploadError.
What i am trying to achieve is to be able to return non-compliance error to users either through putting a message in the div (preferred method) or alert.
Looking at the closest solution How to trigger uploadify onError event handler, but it's outdated as it's for v2.
Using the same method as the outdated post up there, I have $("#fileInput").uploadify() with onUploadError added:
'onUploadError' : function(file,errorCode,errorMsg) {
var r = '<br />ERROR: ';
switch(errorMsg) {
case 405:
r += 'Invalid file type.';
break;
case 406:
r += 'Some other error.';
break;
}
alert(r);
setTimeout('$("#fileInput'+ ID + 'span.data").html("'+r+'");',111);
}
The problems I am having right now are:
Alert returns undefined using the codes above
setTimeout doesn't do anything
How can you solve these problems?
Maybe it's a little too late... but anyway I try to answer.
I'm also playing around with v3 of uploadify. onError() does no longer exists, it has been replaced by onUploadError(). The erroror object given by the old onError event does no longer exists. Now to check for the type of error you can switch on the errorCode argument (the second given in the callback), which is numeric. I've not found a table with all possible error codes, but doing some trials I discovered the following three error codes:
-200: HTTP errors (e.g. HTTP 500, 400, 404, etc.)
-220: IO errors (e.g. connection closed without response from the server, or errors while rading the source file from the user's PC)
-280: don't have actually fully understood what kind of errors they are, but is seems to be errors gracefully handled by uploadify. For example, if you try to add to the queue a file that is already in the queue, uploadify ask you whether you want to replace the file that's currently enqueued, or cancel the operation. If you cancel, an error is fired with code -280.
To check for the specific type of error, for example to get the specific HTTP error code (in case the error is an http error), you can check the error message, which is the third argument. This argument is a string, not a number, so you cannot use a switch .. case as in your example (or at least it's not that simple to use a switch .. case with strings). Simply use an if .. else if .. else.
Hope this can help...
I'm still looking for a complete list of the possible error codes given in the errorCode argument of the event handler. If someone knows, please tell me!