Hello!
I hope you're doing well, and we apologize for the delayed response and the trouble.
Please ensure you have the latest version of Acrobat installed on the machine: 25.001.2043x. Optional update, Mar 19, 2025. Check for any pending updates from the Menu > help > check for updates, install the updates, restart the app and the machine, and check. For more information, see this: https://adobe.ly/42jgGYB
Do you get the error when using the desktop version or online services? Open the PDF and go to File > Properties > Security. Ensure that signing is allowed. If not, you may need to supply the permission password to change the settings. Ensure your digital ID is correctly set up. Go to Edit > Preferences > Signatures > Identities & Trusted Certificates > Moreand verify your digital ID. See this article for more information: Manage Digital IDs in Acrobat
Let us know how it goes after trying the above suggestions, and from our community expert.
Thanks,
Anand Sri.