We designed some of the PDF's in AEM forms 6.3 using Designer.
We are using some UI data to pull it in forms by calling service when we click on button in UI.
It is showing the error "There was an error opening this document. The file is damaged and could not be repaired."
when im adding some extra data and generating the document.
Can someone tell me where is the issue and some solution ?
If the error is true, it can be extremely difficult to find problems in the PDF syntax and find them. If you can figure out that nature of what's wrong, we might be able to see what led to that. Can the PDF be opened in Acrobat? There are some fixup tools in Acrobat's Print Productions > Preflight tool that can sometimes restore consistency. Tell more about the life cycle of the PDF?
Adding to what Matt mentioned above here is how you can check via preflight:
By any chance are you transferring the pdf over the network?