Check the accepted formats
Most form errors happen because the website accepts only a few extensions. Look for JPG, JPEG, PNG, or PDF in the instructions before converting.
Best first fixes
Convert HEIC, AVIF, or WebP to JPG for normal photos. Use PNG for screenshots or graphics. Use JPG to PDF when the form expects a document instead of an image.
Check file size
A supported format can still fail if the file is too large. After converting, confirm the file size and open the output before submitting.