Adobe Reader or Acrobat displays a At least one signature has problems message when signed PDF is opened - Foxit PDF SDK

Adding the certificate that was used to apply the digital signature into Adobe's list of Trusted Identities by some easy steps.

How to block users from modifying the text in your Adobe Acrobat document ( PDF) - Quora

At least one signature is invalid in Adobe Reader – Addo Sign Support

PDF Signature invalid on Adobe Acrobat Pro DC, but - Adobe Community - 14104417

Adobe Reader or Acrobat displays a At least one signature has problems message when signed PDF is opened. Signature validity is UNKNOWN. Signer's identity is unknown.

Adobe Reader or Acrobat displays a At least one signature has problems message when signed PDF is opened. Signature validity is UNKNOWN. Signer's identity is unknown.

PDF shows signature in Foxit Reader but not Adobe Reader - Stack Overflow

Cannot Validate Digital Signature / Signature is Unknown – Help Center

User Manual « Docear

Use Foxit PhantomPDF to open Embedded Adobe Acrobat Documents and Embedded Foxit Reader Documents in Microsoft Office – Help Center

Error when signing PDFs with Adobe Acrobat Reader DC - certSIGN

How to fix the error 'Adobe Reader could not open because it's either not a supported format or has been damaged' - Quora

FoxIt message At least one signature has problems, cannot edit the .pdf – Rocky Mountain Human Services

PDF) Shadow Attacks: Hiding and Replacing Content in Signed PDFs

PDF) Shadow Attacks: Hiding and Replacing Content in Signed PDFs

Turning off Adobe's ability to scan all of your organization's documents for generative AI : r/sysadmin