Error message

• Warning: getimagesize(public://slideshowpics/slide_spadüs2_hp_1.jpg): failed to open stream: "DrupalPublicStreamWrapper::stream_open" call failed in template_preprocess_field_slideshow() (line 958 of /homepages/31/d236128125/htdocs/behncke-architects-update-2020-07-03/sites/all/modules/field_slideshow/field_slideshow.module).
• Warning: getimagesize(public://slideshowpics/slide_spadüs2_hp_2.jpg): failed to open stream: "DrupalPublicStreamWrapper::stream_open" call failed in template_preprocess_field_slideshow() (line 958 of /homepages/31/d236128125/htdocs/behncke-architects-update-2020-07-03/sites/all/modules/field_slideshow/field_slideshow.module).