I'm upgrading my client's website from EE 2.5.5 to bring it up to current spec. I'm at the first stage, going from 2.5.5 to 2.11.9. The site has a number of modules, including CartThrob (currently 2.1.4). (It's all very old, I know.)
After running the EE upgrade, at the end of the installation wizard process I get an error message, and visiting the admin page I now get the following:
A PHP Error was encountered Severity: Notice
Message: Undefined property: Wizard::$functions
Line Number: 650
Fatal error: Call to a member function insert_action_ids() on null in /path/to/system/expressionengine/third_party/cartthrob/language/english/cartthrob_lang.php on line 650
(server path hidden by me!)
Is this a basic incompatibility between the current version of CT and EE 2.11.9, so I'd need to upgrade CT before upgrading EE, or is there something else going on?
Also is there any general advice about upgrading EE and modules? Should the modules be upgraded first or does EE go first? I've searched the documentation and not found a clear answer.
Any help appreciated.