As discussed here, this error message:
Sorry, this image cannot be processed. It may be too large or complex. Please contact us for help.
is misleading, as it is not the file size (which was less than 10 MB) but the pixel size of the image.
How about instead stating:
Sorry, this image cannot be processed. The image is too large (greater than 2,500 × 1,200 pixels). Please reduce the image size to fewer pixels and retry.
And replace 2,500 × 1,200 in the message with whatever the actual pixel size limit is.
Note the current error leaves behind cruft images that are partially uploaded and remain leaving detritus behind as useless Wikitree files. For example, see:
So in addition to clarifying the error message, the code needs to be fixed to not leave behind junk files when the error occurs.