Error creating a journal when more than one lang is enabled in site

[marcbria]

Describe the bug
OJS stable-3.3, with more than one lang enabled (tested with en_US, es_ES and ca_ES and en_US as primary lang).
When creating a new journal, the journal is created but an "An unexpected error has occurred. Please reload the page and try again." error message is shown and the modal is not closed.

• No log info left in server side.
• No clear infor left in client side in Firefox.
• An "ERR_CONNECTION_CLOSED" error is shown in Chrome's console when reaching "https://foo.com/_/api/v1/contexts"

IMPORTANT: Not able to reproduce this same issue with a host installation (without docker) so I'm doing further testing to identify the error better.

To Reproduce
Steps to reproduce the behavior:

1. Create new OJS version stable-3.3.0 (dockerized)
2. Enable 3 langs (en_US, es_ES and ca_ES) and set en_US as primary lang.
3. Create journal and enable all langs setting en_US as primary.
4. See error

If only one lang is enabled, the error is not shown.

What application are you using?
OJS stable-3.3.0 with docker official images behind a reverse proxy (traefik) with minimal mod_rewrite rules.

Additional information

No other references found in forum, github or stackoverflow except for this one, that don't help fixing the issue:
https://stackoverflow.com/questions/38752691/neterr-connection-closed-error-at-chrome-with-http2-0-nginx

[marcbria]

Not able to reproduce this same issue with a host installation (without docker) so I'm doing further testing to identify the error better.