Solution of Removing maintenance page from wordpress after upgrading plugins/core
A file named .maintenance is placed by WordPress during an automatic upgrade to notify visitors that the site in under a short maintenance. If an upgrade fails or is corrupted, the file will remain in the WordPress folder and won’t get deleted.
To remove .maintenance file,
- Access your wordpress root directory via FTP.
- Locate the file .maintenance.
- Remove the .maintenance file from the wordpress root directory.
Once you solve this problem, you may want to run the WordPress automatic upgrade again.