Exchange of expired preflight signature
in older Acrobat versions

On 6.11.2020 the Adobe preflight signature has expired.

On 3.11.2020 Adobe released just in time updates for Acrobat DC, 2020 and 2017 with a new preflight signature (valid until 22.10.2025).

Since there are unfortunately no more updates for older Acrobat versions from Adobe, you have to fix it yourself!


Exchange of the preflight signature

First you must get your hand on the new signature. Either from a user of the latest update of Acrobat XI or DC or from an installation of the free trial version of Acrobat DC. (Don’t forget to change the default by unchecking the “Remove earlier version” option in Acrobat downloader UI.)

The signature is in the file Preflight.p12 which is stored in the following directories:

  • MacOS X (* Show Package Contents with a right mouse click)
    • Acrobat DC: … > Applications > Adobe Acrobat DC/2020/2018/2015 > Adobe*
      > Contents > Plugins > Preflight.acroplugin > Contents > Resources
    • Acrobat XI Pro: … > Applications > Adobe Acrobat XI Pro > Adobe Acrobat*
      > Contents > Built-in > Preflight.acroplugin > Resources
    • Acrobat X Pro: … > Applications > Adobe Acrobat X Pro > Adobe Acrobat*
      > Contents > Built-in > Preflight.acroplugin > Resources
    • Acrobat 9 Pro: … > Applications > Adobe Acrobat 9 Pro > Adobe Acrobat*
      > Contents > Plug-ins > Preflight.acroplugin > Resources
  • Windows
    • 32bit: c:\Program Files\Adobe\Acrobat <version>\Acrobat\plug_ins\Preflight\
    • 64bit: c:\Program Files (x86)\Adobe\Acrobat <version>\Acrobat\plug_ins\Preflight\

Maybe admin credentials are required to access these folders in your installation.

The old file Preflight.p12 in Acrobat 9 – XI must be replaced by the new file Preflight.p12 (created in 2020) from Acrobat DC. After a restart of Acrobat the problem should be gone.

Validation of new signatur

Sometimes the new signature is not sucessfully validated when an PDF with an embedded preflight audit trail is opened. In this case the new signature must first be added to the trusted certificates in  Acrobat (or in Reader) once:

  • Open a PDF with a preflight audit trail using the new signature
  • Open the Signature Panel (using the button in the blue bar on top right)
  • Select the signature entry and Show Signature Properties… (with a right mouse click)
  • Show Certificate… (Acrobat 9/X) or Show Signer’s Certificate… (Acrobat XI/DC)
  • Tab Trust
  • Add to Trusted Identities… or Add to Trusted Certificates + OK
  • Option Use this certificate as trusted root + OK
  • (Close all signature windows)
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