Problem by setting new PHP version

Here are the error logs:

[Tue Sep 27 23:08:44.208669 2022] [php:warn] [pid 6664] [client 146.241.63.89:0] PHP Warning: Attempt to read property "special" on null in /home/public/sites/www.hhgrijssen.nl/libraries/src/UCM/UCMType.php on line 169, referer: hhgrijssen.nl/administrator/index.php?op...xicontent&view=items
[Tue Sep 27 23:08:44.208702 2022] [php:warn] [pid 6664] [client 146.241.63.89:0] PHP Warning: Attempt to read property "prefix" on null in /home/public/sites/www.hhgrijssen.nl/libraries/src/UCM/UCMType.php on line 169, referer: hhgrijssen.nl/administrator/index.php?op...xicontent&view=items
[Tue Sep 27 23:08:44.208708 2022] [php:warn] [pid 6664] [client 146.241.63.89:0] PHP Warning: Attempt to read property "special" on null in /home/public/sites/www.hhgrijssen.nl/libraries/src/UCM/UCMType.php on line 169, referer: hhgrijssen.nl/administrator/index.php?op...xicontent&view=items
[Tue Sep 27 23:08:44.208713 2022] [php:warn] [pid 6664] [client 146.241.63.89:0] PHP Warning: Attempt to read property "type" on null in /home/public/sites/www.hhgrijssen.nl/libraries/src/UCM/UCMType.php on line 169, referer: hhgrijssen.nl/administrator/index.php?op...xicontent&view=items

its appache log put joomla error in browser (after actived error reporting to maximum)

No other error is shown in the browser than I gave on the printscreen in a previous message (with error reporting on maximum).

kath did you re check your site ? demo working for me
i create a test micker item

Today, I have a similar error when I want to edit items from a specific category. this category shows a list of items whose titles are hidden (but I have tested and this is not the cause of the problem). However, I do not encounter any problems to edit other items of other categories. only differences: the items I cannot edit have been imported.
I created this site last week then categories, types and fields and 1 item. or it did not appear on the site. it only appeared when I changed PHP 7.4.30 for PHP 8.0.23 (I now test PHP 7.4.30 again and it works : I can see all items).

With PHP 8.1.10, I encounter some PHP deprecated errors but I noted that FC wasn't yet ready for PHP 8.1

Since PHP 7.4 now allows me to edit the items, I find that I can edit all the items (since the frontend because from administrator I have always been able to edit all the items).
I hope to help find solutions or answer some questions.

hello thnks for your return but can you specify flexicontent version 4.1.3 ? or last master version ?