after ftp-uploading images to a new folder i decided to move the folder somwhere else.
when checkin the frontend i got following error:
8 getimagesize(): Read Error!
File: var/www/vhosts.............app/parser/slir/slirimage.class.php Line 405
after re-upload all seems fine now. So maybe there was some background-process (resizing ?) during the folder-move that caused to interrupt and break things apart ?