K6 '0' response code and given request didn't reach server

We are using K6 tool to test our application which is hosted in Azure server. While executing the script, we are receiving 0 response status code for few of our requests.

For example, we are triggering nearly 200 Vus with 100 iterations in K6 script, each iteration have http calls and websocket connection. More than 95% of requests are working as expected, but for few requests we are receiving 0 response code instead of 200 response. We set http request timeout as 120s. Nearly 50 API calls are getting 0 response code.

We have analyzed about this issue using Azure app service logs and we found that particular call’s log are not available in the log which means calls didn’t reach server.

It will be appreciated if anyone help me on this issue.

Hi @immaculate,

When k6 gets a 0 status error code it usually means some system issue (like we couldn’t dial the server in time).
The original error is logged on the cli and also there is error_code and error (smaller version of the original error) tags in the emitted metrics. So if you look at those you can actually diagnose this issue better. There is also a page with the error codes and what they mean.

edit: I update the link as I was linking to the CI build :man_facepalming:

I am also getting this zero response status code, and it happens very fast, so I presume K6 is failing to dial the server, but I don’t know how to get around it? Do you any idea @mystoykov

@kasongoyo that depends a lot on what the actual error is and you haven’t provided any info on that so :man_shrugging:

I’m also getting a similar error. When I check the http_req_failed metrics the status code says 0, the k6 error code says 1000, and the message says service unavailable.

any clues ??