OSX fix Selenium Chromedriver launch error spawn Unknown system error -86 Bad CPU type in executable? - macos

Question

Suddenly on the afternoon of January 6, 2021, my Selenium Protractor tests under OSX stopped working with the mysterious error
spawn Unknown system error -86
I did some research and discovered that error number 86 is the same as
Bad CPU type in executable
and ran the following to compare the cpu architecture of my chromedriver binary to my system:
% file chromedriver_87.0.4280.88
chromedriver_87.0.4280.88: Mach-O 64-bit executable arm64
% uname -a
Darwin kobl179273m 19.6.0 Darwin Kernel Version 19.6.0: Thu Oct 29 22:56:45 PDT 2020; root:xnu-6153.141.2.2~1/RELEASE_X86_64 x86_64
% uname -p
i386
How can I fix the chromedriver binary used by my Selenium so that it will run on my Intel x64 mac and clear the "system error -86" or "Bad CPU type" message?

Answer 1

The issue is described in https://github.com/angular/webdriver-manager/issues/476.
This has been now fixed in 12.1.8 so just update to that webdriver manager.
For most users this can be accomplished with
npm uninstall protractor && npm install protractor

Answer 2

Edit: this answer should be considered deprecated now that the underlying bug in webdriver-manager has been fixed. A better solution would be to upgrade to the newest version of webdriver-manager. The answer below may be useful if people need to use an older version of webdriver-manager which still has the bug.
As per Deepak Srinivasan's comment above, this error is caused by https://github.com/angular/webdriver-manager/issues/476
Root Cause:
The ChromeDriver team added "_m1" to the end of the filename for their Apple Silicon ARM builds of Chromedriver -- but both the Silicon and Intel versions of chromedriver have "mac64" in the filename, and the version number is exactly the same. This causes webdriver-manager to always download the Silicon build of Chromedriver, even on Intel macs. As a general solution, simply avoid using the chromedriver that has _m1 in its filename if you are on an Intel mac.
Solution 1: Downgrade to Chrome 86.0.4240.198 and Chromedriver 86.0.4240.22. These versions work together and are the most recent versions prior to the new and problematic support for Silicon ARM
Chrome 86 download page:
https://google-chrome.en.uptodown.com/mac/download/2920124
Disable auto-updates in Chrome: https://superuser.com/questions/1359017/how-do-i-disable-automatic-updates-of-google-chrome-on-mac-os-x
Chromedriver 86: https://chromedriver.storage.googleapis.com/index.html?path=86.0.4240.22/
% webdriver-manager update --versions.chrome=86.0.4240.22
Solution 2: Modify the webdriver-manager npm package to point to the correct chromedriver (thanks to ciekaway from the angular github issue page for this fix)
Modify the following file
node_modules/webdriver-manager/built/lib/files/file_manager.js
or, if using protractor
node_modules/protractor/node_modules/webdriver-manager/built/lib/files/file_manager.js
Near the top of the downloadFile method around line 166, add the following line to remove "_m1" from the name of the file:
fileUrl.url = fileUrl.url.replace(/_m1/, '');
It needs to be after the beginning of the .then block that starts with
binary.getUrl(binary.version()).then(fileUrl => {
it also needs to be before the next reference to fileUrl.
For example:
binary.getUrl(binary.version()).then(fileUrl => {
binary.versionCustom = fileUrl.version;
fileUrl.url = fileUrl.url.replace(/_m1/, '');
let filePath = path.resolve(outputDir, binary.filename());
Note that this solution is temporary. It will be overwritten by an npm install. The Chromedriver and/or the webdriver-manager team will probably fix this issue, at which point you should clear the modified version of your webdriver-manager and download the fix from npm.

Answer 3

For macOS Catalina Version 10.15.6 (19G73)
In my case I was working with Rails and Capybara for feature tests. What worked for me was
First, find the actual chromedriver location running:
which chromedriver
# Which returned:
/Users/alex/.webdrivers/chromedriver
Then, install chromedriver via Homebrew:
brew install chromedriver
Then, remove old chromedriver reference found at previous location with:
rm /Users/alex/.webdrivers/chromedriver
Now, link the old chromedriver reference to the one installed with brew:
ln -s /usr/local/bin/chromedriver /Users/alex/.webdrivers/chromedriver
Then, open Finder app, then click on Go menu and then click Go to folder ... option, and enter this route:
/usr/local/Caskroom/chromedriver/
There you should see a folder with the chromedriver version you have installed, something like this:
88.0.4324.96
Enter that folder and you should see the chromedriver binary file.
Right click on it, and click on Open
Now, you should get a terminal window popping up with the output:
Last login: Sun Jan 31 12:29:15 on ttys001
/usr/local/Caskroom/chromedriver/88.0.4324.96/chromedriver ; exit;
  ~  /usr/local/Caskroom/chromedriver/88.0.4324.96/chromedriver ; exit;
Starting ChromeDriver 88.0.4324.96 (68dba2d8a0b149a1d3afac56fa74648032bcf46b- refs/branch-heads/4324#{#1784}) on port 9515
Only local connections are allowed.
Please see https://chromedriver.chromium.org/security-considerations for suggestions on keeping ChromeDriver safe.
ChromeDriver was started successfully.
Finally, press Ctrl+C to stop the execution and quit the terminal window.
Now, you should be able to run capybara tests.

Answer 4

npm uninstall protractor && npm install protractor

Answer 5

If you use webdrivers gem, upgrade it:
bundle update webdrivers