Recently I upgraded an EE2 website to EE5. After upgrade, everything working very well except I am getting error while trying to edit/create a template from CP or from Template Manager -> Template Settings. For error message, please see screenshot -
So that is an
E_NOTICE level warning, not a fatal error. You are seeing this because you either have debugging forced in your
index.php for you Control Panel, have it hard-coded in your
config.php file, or have it turned on in Output and Debugging in Control Panel.
If you still get a rendered page at
I have noticed these issues in EE4 and EE5 when using the template manager, but they appear harmless, as
E_NOTICE level warnings often are; most full application and their relevant technology stacks can output warnings and notices and log them as well, and be fully functional. Also remember that EE can run on a pretty wide range of PHP and MySQL versions, and that can be very relevant as to what warnings and notices you may get.
If you are truly concerned, contact EllisLab about this, but there is a good change they will tell you to turn off debugging and ignore this notice. You also shouldn't be running a production application with debugging on, ever.