The Document Is Malformed
A malformed document is a document that has structural or formatting errors or is corrupted or incorrectly encoded. In some cases, malformed documents may be recovered within the application used to create the document by using its built-in repair capabilities.
If a gif is malformed, the best way to resolve the issue is to remake the gif. Once complete, render the gif and reinsert it into the desired document before uploading it to Panorama.