404 errors with APIv4 has incorrect content-type header

[NicolasCARPi]

Version used: 6.6.2 in Docker.

Summary

The 404 response sent by apiv4 have a content-type header of text/plain; charset=utf-8 instead of application/json. But the documentation states that all responses are application/json.

Steps to reproduce

Access an invalid api endpoint or none at all:

• https://example.com/api/v4/notjson
• https://example.com/api/v4/

Expected behavior

The response header content-type should be application/json and the response should be displayed in the browser as json (firefox pretty prints json responses).

Observed behavior (that appears unintentional)

The error message is displayed as text instead of being interpreted as JSON.

Possible fixes

Ensure 404 handler sends correct headers, unless of course this is intentional design, in which case I would be interested in knowing the reason ;)

Thanks for the great software everyone and have a terrific day! 🚀

[agnivade]

Great catch @NicolasCARPi !

This is happening because the 404 handler is not wrapped in web.Handler which adds the application/json header. The line is here: https://github.com/mattermost/mattermost-server/blob/6adbcc5d05b9296135f685a08075e278a377603e/api4/api.go#L315.

If you are feeling up to it, please do send a PR, and we'll be happy to take a look.

[NicolasCARPi]

Sorry I am not familiar enough with the codebase to try and fix that by myself :/

[amyblais]

Opened https://mattermost.atlassian.net/browse/MM-46605.

[agnivade]

@amyblais - Let's create this issue itself as an HW ticket. I will close the JIRA issue.

[clementbowe14]

Can I take on this issue?

[agnivade]

Go ahead @clementbowe14 !

[safakkizkin]

@agnivade
It's been a long time no activity here, if it's ok I can do it!