Comment to 'V12.1.0 installed, want to go to v13.1.0 only'
  • It's 'normal' behavior of the site going into maintenance mode after an update. It saves the site from crashing after you did a site update and before you updated related version modules. You need to unlock your site by removing the auto-generated maintenance file in your web root folder, by using WebFTP or FTP. On a local installation just delete the file.