Steps to replicate this issue:
- Try to add a new section by clicking on "Add topic" on any talk page on Beta cluster or try to open this URL:
Observe that, neither the new topic tool nor the old tool for adding new section opens up, instead it shows a page with error "Service Temporarily Unavailable".
The issue doesn't seem to be Discussion Tools specific. I tried it after disabling Discussion Tools from Beta features, and also after disabling the new topic tool option from #mw-prefsection-editing, it still shows the same error.