The solution is to get the latest stable version of Adobe Acrobat Professional for your organization. Keep in mind that just having version 10 of Adobe will not fix the certificate issue for extensions. Either obtain a patch for your organization from your Adobe representatives or get the latest DC version. One last note: be sure to keep Adobe Acrobat and Adobe Reader in synch as far as versioning.
Usually Affects Organizations and Not Individuals
Although you can save the AEM-Generated PDF, you may find you can’t save with extensions. You may receive the error, “This document could not be Reader Enabled.”
This is due to a certificate needed by the AEM product for your organization as explained in the following Experience League note, https://experienceleague.adobe.com/docs/experience-manager-65/forms/administrator-help/configure-acrobat-reader-dc-extensions/updating-expired-reader-extension-certificates.html?lang=en
Key Information from the article
“…Adobe leverages a public key infrastructure (PKI) to issue digital certificates for use in licensing and feature enablement. Adobe has been issuing certificates under the certificate authority Adobe Root CA, which is set to expire on January 7, 2023. The expiration of certificate does not impact PDF documents extended using production certificates issued from the Adobe Root CA based certificates (old certificates). All PDF documents, Reader extended using the old certificates before January 7, 2023, including the ones downloaded by your customers, would continue to work with all the usage rights that are applied to them, and do not require any updates.
A new certificate authority, Adobe Root CA G2, and certificates based on the new certificate authority are now available. On or before January 7, 2023, start using the new certificates — those based on Adobe Root CA G2 — to Reader extend your new PDF documents. You can obtain new certificates from the Adobe Licensing Website or Adobe Support…”