problem after migration to J!4. 500 behavior::framework not found.

[RvJoom]

Hello
After migrating from 3.10 to 4.4, it seems that I have 2 problems in error messages

1) front-end side (cassiopéa is configured by default) :

500 behavior::framework not found.
TPL_PROTOSTAR_BACKTOTOP ​

2) backoffice side (it works correctly except that it is impossible to save a change in the configuration)

Bad Request
Your browser sent a request that this server could not understand.

regards

[Per Yngve Berg]

Mod. Note: Relocated Topic from Installation to the Upgrade Forum.

[Per Yngve Berg]

Please use the Forum Post Assistant. See Red Frame above.

Perhaps you have a copy of the J3 Template Protostar remaining.

[RvJoom]

Hi

Thanks

1/ There were specific themes probably based on protostar on the old J3 version even if I had not activated it. By moving these directories in a backup, I see cassiopéa but without anything. I think that we will have to find and reassign everything that existed!

2/ unresolved problem

[sakiss]

Your problem is probably coming from a 3rd party extension using Mootools.
Enable the "System Debug" from your global configuration to get to know the file and code that produces that.

[RvJoom]

Hi
Thank you for your contribution.
I've already activated the debug max mode. but I have nothing more than this message

Bad Request
Your browser sent a request that this server could not understand.

[gws]

If you want help, Please use the Forum Post Assistant. See Red Frame above.

[RvJoom]

Hi
I don't understand your request? Why? I said it all! No?
Maybe my bad English

[toivo]

I don't understand your request?

Please post the results from the Forum Post Assistant (FPA) by following the instructions in the link above in the red banner, https://forumpostassistant.github.io/docs/ so that the configuration, including the versions of the third party extensions, can be reviewed by our volunteer Joomla experts.

[RvJoom]

Hello
I understood. I went to step 7
I launched https://www.domain.tld.cc/fpa-en.php but I have a
HTTP ERROR 500

in configuration.php I have:
public $debug = '1';
public $error_reporting = 'maximum';

[sakiss]

Possibly there are issues with your server.
If possible get a backup and try that elsewhere