Hi @Jonas_George @jking ,
I wrote that guide; I'm glad it is finding use!
Like you both, I recently ran into this issue as well. Here is my post about it: ODK Central 2025.3 cannot login due to 401 DELETE /users/session/current .
You could try adding the x-forwarded-proto: 'https' header to your reverse proxies and see if that solves the issue. ODK recently changed its authentication ruleset and now requires HTTPS, which interferes with reverse proxies that do not have this header.
If that doesn’t work (for some reason), the nuclear option is to just comment out the new code found in lib/http/preprocessors:
If you comment out lines 102 and 103 above, this will give you back access to the server over HTTP in my testing.
Best of luck!