OSX Dropbox Sync API Error - unable to verify link request - macos

Question

Coded in Swift I implemented after the Tutorial.
DBAccountManager is setup in AppDelegate on applicationDidFinishLaunching.
Later, when the user activates dropbox support in my application I'm trying to link the account.
The Window Panel is displayed and my application is waiting for the callback.
Sometimes I do not get a linked account, even the user logs in and accepts.
The Log says
"[ERROR] unable to verify link request"
When this occurs on a machine it wont't work, you can retry and retry...
if it worked, it works like a charm and in future I always get the linked account directly from the library without the login window.
What does this error mean and what can I do?
AppDelegate:
func applicationDidFinishLaunching(aNotification: NSNotification) {
// Dropbox API Key & Secret
let _appKey = "------"
let _appSecret = "------"
// Accountmanager
if (DBAccountManager.sharedManager() == nil)
{
let accountManager = DBAccountManager(appKey: _appKey, secret: _appSecret)
DBAccountManager.setSharedManager(accountManager)
}
....
}
The linking in my class, when user clicked to activate dropbox:
internal func __start(parentWindow:NSWindow?, callback:((Bool) -> Void))
{
let am = DBAccountManager.sharedManager()
if am == nil
{
NSLog("Dropbox not available!")
callback!(false)
return
}
// link account
let linkedAccount = am!.linkedAccount
if (linkedAccount != nil)
{
// Already linked
DLog("Dropbox link found.")
let fileSystem = DBFilesystem(account: linkedAccount!)
DBFilesystem.setSharedFilesystem(fileSystem)
callback(true)
}
else
{
// link with window must be in mainthread
dispatch_async(dispatch_get_main_queue())
{
am!.linkFromWindow(parentWindow) {
account in
if (account != nil)
{
DLog("Dropbox linked")
let fileSystem = DBFilesystem(account: account!)
DBFilesystem.setSharedFilesystem(fileSystem)
callback(true)
}
else
{
DLog("NOT LINKED (Dropbox)")
callback(false)
} // if - else account
} // accountmanager block
} // dispatchblock main
} // if - else linkedaccount
}
Here the full log, the app is not doing anything else:
2015-02-23 10:25:39.443 TestApp[39226:30958267] Dropbox init
<<<< MediaValidator >>>> mv_ValidateRFC4281CodecId: Unrecognized codec 1.(null). Failed codec specific check.
<<<< MediaValidator >>>> mv_LookupCodecSupport: Unrecognized codec 1
[10:25:40.979] mv_LowLevelCheckIfVideoPlayableUsingDecoder signalled err=-12956 (kFigMediaValidatorError_VideoCodecNotSupported) (video codec 1) at line 1851
<<<< MediaValidator >>>> mv_TestCodecSupportUsingDecoders: Unrecognized codec 1
<<<< MediaValidator >>>> mv_ValidateRFC4281CodecId: Unrecognized codec 1.(null). Failed codec specific check.
<<<< MediaValidator >>>> mv_LookupCodecSupport: Unrecognized codec 1
[10:25:40.979] mv_LowLevelCheckIfVideoPlayableUsingDecoder signalled err=-12956 (kFigMediaValidatorError_VideoCodecNotSupported) (video codec 1) at line 1851
<<<< MediaValidator >>>> mv_TestCodecSupportUsingDecoders: Unrecognized codec 1
2015-02-23 10:25:43.873 TestApp[39226:30958267] [ERROR] unable to verify link request
2015-02-23 10:25:43.879 TestApp[39226:30958267] NOT LINKED (Dropbox)

Answer 1

I have same issue [ERROR] unable to verify link request after long research and studying the DropBoxSDK I come to the point that this error occurs when state ID is different from value saved at key KDBKLinkNonce. Every time at new Session it generates new state ID. See below code of [[DBSession sharedSession] handleOpenURL:url] method.
- (BOOL)handleOpenURL:(NSURL *)url {
NSString *expected = [NSString stringWithFormat:#"%#://%#/", [self appScheme], kDBDropboxAPIVersion];
if (![[url absoluteString] hasPrefix:expected]) {
return NO;
}
NSArray *components = [[url path] pathComponents];
NSString *methodName = [components count] > 1 ? [components objectAtIndex:1] : nil;
if ([methodName isEqual:#"connect"]) {
NSDictionary *params = [DBSession parseURLParams:[url query]];
NSString *token = [params objectForKey:#"oauth_token"];
NSString *secret = [params objectForKey:#"oauth_token_secret"];
NSString *userId = [params objectForKey:#"uid"];
NSString *state = [params objectForKey:#"state"];
NSString *nonce = [[NSUserDefaults standardUserDefaults] objectForKey:kDBLinkNonce];
[[NSUserDefaults standardUserDefaults] removeObjectForKey:kDBLinkNonce];
[[NSUserDefaults standardUserDefaults] synchronize];
if (![nonce isEqual:state]) {
DBLogError(#"unable to verify link request");
return NO;
}
[self updateAccessToken:token accessTokenSecret:secret forUserId:userId];
} else if ([methodName isEqual:#"cancel"]) {
DBLogInfo(#"DropboxSDK: user cancelled Dropbox link");
}
return YES; }
For further reference please check this link dropbox-sdk-ios

Answer 2

I found something and since I found a fix for that, even the dropbox error is gone.
The problem seems to be, that NSUserDefaults did not store any data (not in memory and not on disk!). Since Dropbox uses NSUserDefaults to check the state before and after, this killed the whole process.
With getting the NSUserDefaults back working it seems the whole dropbox problem was gone.
OSX NSUserDefaults not Working