And if i try to copy-paste "some" html code into the editor ...
it comes "website not response" after a min...
PERHAPS
it will be cool, if source-code can be uploaded on same way as images, sure as .txt format,
and than "imported" from the editor by clicking on this txt file full code??

OK here also ...
in THIS forum text field i can not upload the amount of source code :(
screenshot attached...

code for self-tests can be download here...

https://drive.google.com/file/d/1RZ93KvceMez8PJWRUt_kR4BUc0jqZedy/vi...

okok
after 10x this site is frozen, you like to wait...
my code is in the field...
sure again 10x and it is on the point to save the editor-block
and after the yes save teh site button comes...
screenshot..

If you post something, please include environment info from Systems & Settings

I think you're trying to upload big picture or unsupported type, which is can't handled by your environment, not the c5 itself.

Hi,
yes normal i did, but in this moment i am locked out of the system ..complete..
Sytem is running up and fine, but the "formular-key" makes trouble, so i cant login...
Next days the move to new webserver is done, after i hope it is fixed on mystery way from allone, or i must find the problem :(
than we can go back to this main problem..