The error message "Proxy Agent Signature Verification Failed" is encountered, typically when the target machine has a BDRShield Integration Service (BIS) agent installed, which has been pushed by a different backup server or BDRShield Client. This error arises due to a mismatch in the Unique Identification Number (UUID) used for communication between the BDRShield Backup Server or BDRShield Client and the BIS agent on the target host. Each BIS agent possesses a unique UUID, and when there is a UUID mismatch, subsequent backups fail with the "Proxy Agent Signature Verification Failed" error.

Before proceeding with the solutions, ensure the following:

1. The target host is not added to another BDRShield server or BDRShield client.

2. The VIS agent is not being used by another BDRShield server or BDRShield client.

If the target host is already added to another BDRShield server or BDRShield client, you have two options:

Option 1: Continue using the existing BDRShield server or BDRShield client:

a) Remove the host entry from the BDRShield server or BDRShield client user interface.

b) Uninstall the VIS agent from the target host using these steps:

1. Go to the Control Panel.
2. Select "Programs and Features" and click "Programs."
3. Locate "BDRShieldIntegrationService" and click "Uninstall."
   

Option 2: If you still want to configure backups from the current BDR server or BDRShield client:

a) Remove the host entry from the BDR server or BDRShield client user interface.

b) Uninstall the VIS agent from the target host using the steps mentioned above.

c) Once these steps are completed, re-add the target host to the backup server or BDRShield client and configure the backups.