This article is for users who are receiving an error that one or more signatures are having a problem.
Sometimes this can apply to multiple signed documents and signatures may intermittently not appear. The error may or may not appear in Adobe Acrobat Reader or Adobe Acrobat Pro; but if they appear in PhantomPDF but not Adobe, it is a good indicator of this being the issue.
The following articles should resolve this issue:
https://kb.foxitsoftware.com/hc/en-us/articles/360044404971-How - to - Automatically - Trust - Digital - ID - for - Digital -Signaturehttps://kb.foxitsoftware.com/hc/en-us/articles/360044405071Signature