In Acrobat or Acrobat Reader, go to Help > About Adobe Acrobat or Help > About Acrobat Reader and check if your application is updated to version 21.005.20058 or later.
If not, go to Help > Check for Updates, and install the latest update available.
On Windows 10 (version 20H1 or later), digitally signing a PDF in the browser using Acrobat or Acrobat Reader plug-in with Protected Mode enabled results in the following error: "The Windows Cryptographic Service Provider reported an error: Access is denied. Error Code: 2147942405".
Update Acrobat or Acrobat Reader to the latest version, and then create a feature-specific registry key
Quit Acrobat or Acrobat Reader application.
Open the registry editor - go to Run (Windows menu + R), type regedit.exe in the Open field, and select OK.
In the registry editor, based on your installed version of the product, go to the version-specific location listed below, and create the key FeatureState at the location; the key may not be present by default.
Under FeatureState, create a key of type DWORD and name it ADC4325829. Change its value to 1 (one).
Close the registry editor.
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