zhizhu
Home / cloud-software / Fix Cloudflare Error 521 on Apache Server - Microsoft Store 502 Bad Gateway: Troubleshooting Guide-Shared Mailbox Migration Troubleshooting for Outlook

Fix Cloudflare Error 521 on Apache Server - Microsoft Store 502 Bad Gateway: Troubleshooting Guide-Shared Mailbox Migration Troubleshooting for Outlook

Updated 2026-06-16 09:01:12cloud-software
Fix Cloudflare Error 521 on Apache Server - Microsoft Store 502 Bad Gateway: Troubleshooting Guide-Shared Mailbox Migration Troubleshooting for Outlook
Likely symptom
Likely cause
Safe rollback

Verification route

  • Repeat the original action, not only a simplified test case.
  • Restart the app or reload the service after configuration changes.