After moving to a new server I get this error:

Data Storage Not Working

Data Storage is not working correctly. Review your data storage configuration and adjust the settings as needed to improve speed and performance of your community.

Error: Class 'IPS\Theme\Cache\class_core_global_forms' not found (0)
#0 /home/www/doc/15667/m****+e/www/system/Theme/Theme.php(926): eval()
#1 /home/www/doc/15667/m***e/www/system/Theme/Cache/Template.php(108): IPS\_Theme::overloadHooks('class_core_glob...', 'IPS\\Theme\\Cache')
#2 /home/www/doc/15667/m***.de/www/system/Theme/Theme.php(777): IPS\Theme\Cache\_Template->exists()
#3 /home/www/doc/15667/m*****de/www/system/Helpers/Form/Form.php(139): IPS\_Theme->getTemplate('forms', 'core', 'global')
#4 /home/www/doc/15667/m*****e/www/applications/core/modules/admin/settings/general.php(48): IPS\Helpers\_Form->__construct()
#5 /home/www/doc/15667/*****e/www/system/Dispatcher/Controller.php(101): IPS\core\modules\admin\settings\_general->manage()
#6 /home/www/doc/15667/m+***e/www/applications/core/modules/admin/settings/general.php(38): IPS\Dispatcher\_Controller->execute()
#7 /home/www/doc/15667/m***de/www/system/Dispatcher/Dispatcher.php(152): IPS\core\modules\admin\settings\_general->execute()
#8 /home/www/doc/15667/m***.de/www/admin/index.php(14): IPS\_Dispatcher->run()
#9 {main}

I can't access anything in the acp. The database server has been converted to MariaDB, before it was mysql.

Have you reviewed the datastore directory permissions?

Permission on ftp is set to 755, this should be fine?

3 minutes ago, Daniel F said:

Have you reviewed the datastore directory permissions?

Permission on ftp is set to 755, this should be fine?

Also check your 'uploads' directory. It looks like the theme cache is having issues, and those files go into the uploads directory.

That depends on your new host. It may need to be 777. 

Thanks to you all datastore is now on 777 uploads is still processing trillions of files to 777 but this doesn't fixed the issue. More ideas? How can I clear the cache or as my host recommended session tables? Will this help? And b.t.w., there's enough free webspace available.

After setting permissions, in the ACP there is a link to Support in the upper right of the screen. That page has a link to clear the system cache. 

Also check any constants.php file and ensure there isnt a path from your old server present

21 minutes ago, Randy Calvert said:

After setting permissions, in the ACP there is a link to Support in the upper right of the screen. That page has a link to clear the system cache. 

I don't have access to this ACP setting.

6 minutes ago, Marc Stridgen said:

Also check any constants.php file and ensure there isnt a path from your old server present

The path is correct.

I don't know if this can be helpful. On my test installation giving "An error occurred (500 Error)"on the front site  (latest release) when I disable the setting "Enable template disk caching?" it works fine.

Please check it again now. I have disabled all your plugins and enabled them again which will have cleared cache there

Make sure the path entered into Template disk cache path is writable. You can delete any existing files in there also.

10 minutes ago, Marc Stridgen said:

Please check it again now. I have disabled all your plugins and enabled them again which will have cleared cache there

Cool, just had to duplicate my style and set to default and it is working fine now. Thanks a lot Marc.

1 minute ago, Ramsesx said:

Cool, just had to duplicate my style and set to default and it is working fine now. Thanks a lot Marc.

No problem. Of course also make sure the path mentioned by Matt above is writable if you are caching templates to disk again