In the Install Tool the section "System environment" informs about missing PHP modules and problematic settings.
E.g. the PHP extensions openssl and fileinfo must be enabled. This can be done by adding (or uncommenting) the following lines in the [PHP] section in php.ini:
On a Windows-based server, these are the extension files:
PHP Caches, Extension Classes etc.¶
There are some situations which can cause what appear to be totally illogical problems after an upgrade:
- If extensions override classes in which functions have changed. Solution: Try disabling all extensions and then enable them one by one until the error recurs.
- If a PHP cache somehow fails to re-cache scripts: in particular, if a
change happened to a parent class overridden by a child class which was not updated.
Solution: Remove ALL cached PHP files (for PHP-Accelerator, remove
/tmp/phpa_*) and restart Apache.