Will check that. Most content files were there from the beginning of K2 - any method to clean them, and only keep what’s actually defined in the corresponding blueprint file?
// Edit:
Well, my problem persists, and it might be even harder to debug:
Now, I enter an image, save the page, visit another page, and everytime I come back, the field has the error shown above. When I change the field name once more, reload the page: I can select an image again! But, when saving, leaving the page, coming back: again, Illegal offset error …