One of the most common EFS issues we see is for an expired Domain Data Recovery Agent (DRA) certificate. It is also one of the easiest things to resolve. You may have seen the error Recovery Policy for this system contains an invalid recovery certificate or ERROR_BAD_RECOVERY_POLICY.
Since you can’t extend the life of a Recovery Agent certificate you will need to remove the expired ones first. You start by opening up the Default Domain Policy and navigating to Encrypting File System. On the right side you will see the expired certificate. Right click on the expired certificate and select All Tasks | Export, and export the file to a .CER format. Although this certificate has expired it can still be used to decrypt files that have already been encrypted with this Recovery Certificate specified. (The original DRA private key resides in the Administrator profile of the first domain controller in the domain. If this profile or domain controller no longer exists you may not be able to use this certificate to decrypt files.) Once this is completed you should delete this certificate from the Policy.