Problem with PBCK or Joomla? [SOLVED]

I´ve migrated a J3-Site to J4, so far all is working well except:
Klicking in PageBuilder any "Select"-Button to select an Background I get following error:


Link to image: Link here

Is this a problem with Joomla itself or a problem with PBCK?
(Deinstall and reinstall PBCK does not help)

Hi
I can not see the details on the image
please paste the text so that I can check the problem
CEd

Pleas use link to googledrive below the image - is this possible?

thanks I did not see it
is there a problem with your "images" folder on your website ? have you removed it ?

No, the folder is there and its right are set with admintools. Should I delete the folder and create a new (With JCE filemanager)?

may be that there is a problem of rights ?
do you have some images in it ?
I have never seen this error before but it looks like it does not manage to find the images in the folder

you can try to rename this folder, and create a new one with few images, and check