Error 500 with Oauth2 and DISABLE_REGISTRATION

[camlafit]

• Gitea version (or commit ref): 1.5.3
• Git version:
• Operating system: Debian stretch
• Database (use [x]):
  • PostgreSQL
  • MySQL
  • MSSQL
  • SQLite
• Can you reproduce the bug at https://try.gitea.io:
  • Yes (provide example URL)
  • No
  • Not relevant
• Log gist:
  2018/12/15 16:39:24 [...routers/user/auth.go:541 handleOAuth2SignIn()] [E] UserSignIn: could not find a matching session for this request

Description

If new registration is disbled and external connection allowed, we get a 500 error on callback url.
Workaround is to set on provider https://gitea/user/oauth2/[AuthnName] without callback part
or enable registration

Should be nice to redirect to association page to link oauth account with existing

Screenshots

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs during the next 2 weeks. Thank you for your contributions.

[jhult]

This might be related to #5005.

[pintman]

experienced the same issue in gitea v1.19.0 go v1.20.2

[lunny]

Can you check whether you are visiting a Gitea address that is not the one you input in the GitHub oauth2 application forms? I found that is a reason caused could not find a matching session for this request.