Digital certificate signatures disappearing in Adobe Acrobat (no error shown)

Question

Hi all,We’re experiencing an ongoing and very disruptive issue with Adobe Acrobat when reviewing and digitally signing PDFs.What’s happening:While reviewing multiple PDFs and applying digital signatures, Acrobat frequently glitches.After signing and saving, the signature disappears with no error message.This forces users to re-open the document and re-sign, sometimes multiple times.Saving, editing, and signing actions are often slow or delayed, which seems related.Impact:PDFs generated by instruments must be reviewed and digitally signed in Acrobat.It can take 1 to 5 attempts for a signature to actually persist.In ~99% of cases, there is no warning or error — the signature simply vanishes after save.Environment notes:Issue occurs across multiple documents and sessions.Happens during normal review/sign workflows (not concurrent editing).Extremely time-consuming and risky for compliance-related documents.Has anyone else encountered this?Any known causes (cloud sync, autosave, incremental save, cert trust, protected mode, etc.) or recommended fixes would be greatly appreciated.Thanks in advance.

excited_elegance398b · Answer

Hi,This is something we’ve been facing in our environment as well and I think I can shed some light on the root cause.What is actually happening?For us, the issue was only happening on PDFs stored in network shares, however depending on how your environment is setup, it may be different for you.When Acrobat commits a signature, it needs to briefly open the PDF with exclusive access (ShareMode: None) to write the signature. IFANY OTHER PROCESShas a handle open on that file at that exact instant, Acrobat’s request for exclusive access fails with aSHARING VIOLATION, and instead of surfacing an error, it silently drops the signature, although depending on the exact moment of that the violation occurs, an error may still occur, that’s why it’s inconsistent.For us, the process grabbing the file at the wrong moment was our endpoint security softwareplus occasionally the Microsoft Defender for Endpoint sensor. They werescanning/reading any files read/modifiedwithin network shares. Because it’s a timing race, its intermittentand it could take multiple attempts to get one where Acrobat “wins” and saves cleanly. For us, it never failed on local drives because our DLP agent didn’t scan files on the local drive at all, depending on your environment, what agents or tools you have running and accessing files, your experience may differ but it’s a good first place to check, see what security tools you are using and what they are configured to scan.I figured this out by using procmon (process monitor) to monitor a folder with a pdf file while I signed and saved it back to that folder. Looking at the logs, I could clearly see the agent repeatedly accessing the file and then Acrobat failing itsexclusive access request with aSHARING VIOLATION.Unfortunately, if you can’t change your antivirus/EDR, DLP, indexing service or whatever it is that is causing the issue for you, there is no settings in adobe you can do to fix this.This is something Adobe needs to fix in Acrobat itself.Other PDF tools don't fail the same way under the same conditions. Some ways Adobe could make signing far more robust could be:Retrying the exclusive open with a short backoff instead of failing on the first sharing violationUsing an atomic write approach (write to temp, then swap) so it doesn't require an uninterrupted exclusive handle at the critical moment.

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