digikam can't save images in PNG format after editing

Good day everyone, is anybody using digikam to edit images? I encountered this bug recently, that digikam fails with an only general error message "Failed to save file" when I try to save an image file in PNG format. It is reproducible like this: 1. start digikam 2. open any image to edit 3. save as: select PNG file --> failure Exspected behavior: 3. save as: should save the converted to PNG format image file Other formats seem to work well, I have tried .jpg, .jp2 In ~/.xsession-errors there are some message which may be related: Opening the image file into the editor: TQFile::open: No file name specified TQFile::open: No file name specified Exif Qt::Orientation: 1 Saving: TQFile::open: No file name specified TQFile::open: No file name specified JPEG image preview size: (1280 x 720) pixels - 80124 bytes libpng error: known incorrect sRGB profile digikam: WARNING: error saving image '/home/user/xyz/lnw39a.digikamtempfile.tmp This tmp file is created with zero size and vanishes after clicking ok in the dialog with the error message. Searching the greatest database of all ages taught me that the libpng error message is commonly known and that something had been changed in handling PNG format which I don't understand really, but my guess is that the interaction of digikam with libpng might be affected. System information: TDE R14.0.5 (PSB) digikam 0.9.6 using PNG library version 1.6.28 Devuan ascii Before I try to find out more and/or create a bug report I'd like to ask if anyone has seen this error and knows what to do about it. Any ideas and hints welcome. Kind regards, Stefan