While upgrading to version 4.5.3 or later, you may face errors and most of those cases are caused by lack of write permissions on "PF.Site/Apps" folder when upgrading phpFox site with "File System" FTP option. In this case, we have some quick solutions for you:

- Solution 1: Update permission 777 to "PF.Site/Apps" folders and its subfolders/files recursively. Then you can follow our guidance to upgrade again and can use "File System" option

- Solution 2: Skip step to upgrading apps with phpFox by unchecking all apps. You can still use "File System" option.

- Solution 3: If you still want to upgrade apps while upgrading phpFox, please use "FTP/SFTP" option which FTP account has write permission on "PF.Site/Apps" folder

If you have faced any other issues or other solutions while upgrading phpFox, feel free to share us here.