I Have the same problem, after update to drupal 8.9.1:
Test 1:
drupal/image_widget_crop 2.3.0
drupal/crop 2.1.0
drupal 8.9.1
test 2:
drupal/crop 2.2.0
drupal/core 8.9.1
drupal/image_widget_crop 2.4.0
drupal 8.9.1
I updated drupal and put the code on a new server with same same php7.2 version
This worked before (same like test1):
drupal/crop 2.1.0
drupal/image_widget_crop 2.3.0
drupal/core: 8.8.7
I got the same error.
Any ideas what i has to check?
I have the Same Problem in Drupal 8.9.1 after updating from Drupal 8.7
Did you find a way to solve the problem?
I get this error-message by using a form with the cropping-funktion:
The file "public://filename.jpg" is not valid on element field_imagename[0][image_crop].