Karma sometimes generates Error: read ECONNRESET after successful test run

Expected behaviour

This started happening intermittently after I upgrade from 3.1.3 to 3.1.4, and it has been happening ever since (not every time – about 1/3 to 1/2 of the time). ( After looking through the changelog, I’m inclined to suspect https://github.com/karma-runner/karma/commit/cc2eff2 )

The error I get is:

$ karma start karma.conf.js --single-run --jenkins
21 02 2019 09:43:38.104:INFO [compiler.karma-typescript]: Compiling project using Typescript 3.2.4
21 02 2019 09:43:53.795:INFO [compiler.karma-typescript]: Compiled 21 files in 15446 ms.
21 02 2019 09:43:57.633:INFO [bundler.karma-typescript]: Bundled imports for 21 file(s) in 3328 ms.
21 02 2019 09:43:59.695:INFO [karma-server]: Karma v4.0.0 server started at http://0.0.0.0:9876/
21 02 2019 09:43:59.720:INFO [launcher]: Launching browsers ChromeHeadless with concurrency unlimited
21 02 2019 09:43:59.757:INFO [launcher]: Starting browser ChromeHeadless
21 02 2019 09:44:01.220:INFO [HeadlessChrome 72.0.3626 (Windows 10.0.0)]: Connected on socket 16JL3Xy0xm-ri3aBAAAA with id 59122393
HeadlessChrome 72.0.3626 (Windows 10.0.0): Executed 0 of 110 SUCCESS (0 secs / 0 secs)
[1A[2KHeadlessChrome 72.0.3626 (Windows 10.0.0): Executed 1 of 110 SUCCESS (0 secs / 0.061 secs)
...
[1A[2KHeadlessChrome 72.0.3626 (Windows 10.0.0): Executed 110 of 110 SUCCESS (2.695 secs / 2.341 secs)
TOTAL: 110 SUCCESS
21 02 2019 09:44:05.251:ERROR [karma-server]: { Error: read ECONNRESET
    at TCP.onStreamRead (internal/stream_base_commons.js:111:27) errno: 'ECONNRESET', code: 'ECONNRESET', syscall: 'read' }
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command

Actual behaviour

Error: read ECONNRESET

Environment Details

Karma version: 4.0.1 Operating System: Windows 10 64-bit

See: https://stackoverflow.com/questions/54809981/how-do-i-debug-errors-from-karma-server

Steps to reproduce the behaviour

Unfortunately I cannot share my repo, since it is private. If someone can guide me on how to track down the source of this error, I’d be happy to do the heavy lifting.

[costescuandrei]

Any update on this? This is still messing up the build on some comps. Maybe the root cause of this should be dealt with as well? Like making it expect the browser disconnect (not fail) or disconnects happening in the reverse order?

[mgroenhoff]

@johnjbarton I sent a PR to fix this issue. This is currently making our automated tests fail because we rely on the exit code being 0.