When I try to digitally sign a PDF in Adobe Acrobat for Windows using a self-created Acrobat Digital ID stored as a PFX file, I get the following error message:

“Creation of this signature could not be completed.”

This happens when I start the digital signature process and Acrobat loads the Digital ID / certificate selection window.

The confusing part is that the signature can still be created. The Digital ID list loads, I can continue signing, the PDF is saved, and when I reopen the PDF Acrobat says:

“Signed and all signatures are valid.”

The error usually appears only on the first signing attempt in a new Acrobat session. After the first attempt, if I close the signing window and try signing again in the same Acrobat session, the error does not appear.

The error also disappears in these cases:

1. If I run Acrobat as Administrator.
2. If I open the signing panel once, close it, and then try signing again.
3. If I first open Preferences → Signatures → Identities & Trusted Certificates → More, close that window, and then try signing.

So the issue seems to happen during the first loading/initialization of the Digital ID / certificate system. The signature itself is created successfully and validates correctly.

I tried the following, but the issue still comes back in normal user mode:

• Removed and recreated Acrobat Digital IDs / PFX files.
• Removed signature appearances.
• Cleared Acrobat AppData folders.
• Reinstalled Acrobat.
• Disabled Run in AppContainer.
• Disabled Protected Mode at startup.
• Cleared Windows certificate cache using certutil.
• Removed Apple/APNS certificate from CurrentUser\My.
• Removed and recreated Microsoft Work/School Workplace Join certificate.
• Checked Windows certificates with certutil.
• The Microsoft Platform Crypto Provider certificate shows “Signature test passed.”
• Office / Work or School account was disconnected and reconnected, creating a new MS-Organization-Access certificate, but the issue still remained.

Based on these tests, the issue does not seem to be caused primarily by a corrupted PFX/Digital ID, a signature appearance cache problem, a damaged Acrobat AppData profile, a simple installation issue, the Apple/APNS certificate, the old Workplace Join certificate, or an invalid final PDF signature.

I cannot fully rule out an interaction with Windows certificate/CryptoAPI/CNG components, but the signature itself validates successfully and the issue persists even after recreating the Microsoft Work/School certificate. The behavior seems to occur during the first Digital ID / certificate loading step in normal user mode.

Current workaround:
I can avoid the error by running Acrobat as Administrator, or by opening and closing the signing/certificate settings once before signing. But Acrobat should not show this error if the signature can be completed and validated successfully.

Adobe Acrobat version: 26.1 / DC Continuous
Windows version: 10.0.26200.8457
Product: Adobe Acrobat desktop for Windows, not Acrobat Reader