Restore ownCloud WebDAV Sync by Finding the Broken Route
Trace the WebDAV request through Apache, Nginx, or a reverse proxy, then confirm ownCloud sync works with an authenticated PROPFIND test.
Every time you sign in to an untrusted device with two-factor verification turned on, you'll receive a security code in your email or on your phone to make sure you're the one signing in. If you've turned off two-step verification, you'll receive and resend security codes periodically and whenever there's a risk to the security of your account. If you don't want to use email, calls, or text messages, you can use the Microsoft Authenticator app to enhance the security of your account and sign in without a password. To enable or disable two-step verification:
Set up 2-factor verification
Proceed to sign in to your Microsoft Office account
Enter the phone number for verification and select “ Next ”
Enter the verification code sent to the phone text message and select “ Verify ”

Authentication is successful, select “ Finish ”
Every time we log in on a strange computer, in addition to the password, we will authenticate via an OTP message sent to the phone, we need to enter the OTP - One Time Password and select " Verify "
In case we regularly use Office 365 on one computer (not shared with others) we can choose “ Do not show this message again ” and confirm “ Yes ”
Turn off the "2-factor authentication" feature
The 2-factor authentication feature brings absolute security to the organization, but it also causes a lot of trouble for ordinary users. To turn off this feature we need to log in with an Admin account and select Admin Center
Next we choose “ Azure Active Directory ”
Continue to select Azure Active Directory >> Properties >> Manage Security Defaults
In the Enable Security defaults option box, click No
When turning off this function, we need to state the reason why it is turned off (For example, you can enter N/A) and choose " Save ".
From now on, Office 365 accounts in the sign-in organization will no longer require two-factor authentication until the administrator turns it on.
Trace the WebDAV request through Apache, Nginx, or a reverse proxy, then confirm ownCloud sync works with an authenticated PROPFIND test.
Fix Nextcloud’s missing outgoing address warning by setting its canonical URL and checking DNS, HTTPS, and reverse-proxy routing from the server itself.
Configure APCu and Redis over a local Unix socket for Nextcloud caching and file locking, with steps for current and older Nextcloud releases.
Check Nextcloud’s cron mode, repair its systemd service and timer, and verify that background jobs run after startup and every five minutes.
Enable reliable Nextcloud file locking, choose the right Redis or Valkey backend, and verify the warning clears without risking concurrent file changes.
Fix common Nextcloud scan findings with current updates, HTTPS and HSTS, precise reverse-proxy trust, and checks against the public server.
Back up Nextcloud’s files and MariaDB together, schedule encrypted Restic snapshots with cron, and verify recovery without risking the live server.
Configure Nextcloud SSE for the storage that needs it, protect encryption keys, and measure transfer and CPU impact before encrypting existing files.
Connect Nextcloud’s file search to Elasticsearch, index document contents, and choose a setup that fits your server and security needs.
Configure Nextcloud to remove deleted files after a defined retention period, schedule background jobs reliably, and avoid commands that purge every user’s trash.