the file's extension, "png", does not match its underlying file type.

Hi Elmucho,

the reson is not really appian related.
Is you file really in the right format?
File format and extension are not the same.

"File extensions also often indicate the file type, or file format, of the file, but not always. Any file's extension can be renamed, but that won't convert the file to another format or change anything about the file other than this portion of its name."
-> for more information:
www.lifewire.com/what-is-a-file-extension-2625879