The message indicates that there is a mismatch in the key used which is most likely related to the encryption file. If you have multiple scanning servers, you can follow the steps in this knowledgebase article: https://www.lansweeper.com/kb/202/password-hash-errors.html
If you cannot restore a working copy of the encryption key file, you will have to re-enter the credentials which you entered under Deployment\Security Options. This will re-encrypt the password with the current encryption key.