The first troubleshooting step we would follow to get a server to backup is to restart the client services and to reset a client file that keeps the incremental tracker of the backup jobs. These instructions are specific based on the Datto client that each machine is using.

ShadowSnap - Agent Version 4.0.0

1. On the machine not able to run a backup, open Windows Services and stop the following services:
1. ShadowProtect Service
2. Storagecraft Raw Agent
3. Storagecraft Shadow Copy Provider
2. Navigate to C:\Program Files (x86)\StorageCraft\ShadowProtect\ShadowSnap.
3. Delete the file endptconfig.sqlite3.
4. Go back to Windows Services and restart the three services from step 1.

Datto Windows Agent - Agent Version 2.2.0

1. Open Windows Services and stop the Datto Backup Agent service.
2. Open file explorer and navigate to C:\Windows\System32\config\systemprofile\AppData\Local\Datto\Datto Windows Agent.
3. Delete the agent.sqlitefile.
4. Start the Datto Backup Agent Service. 

After this, repair the communication between the Datto appliance and the protected machine and test the backup process, using the procedure below:

1. Open up Remote Web for the Datto device.
2. Click on the Protect tab.
3. Find the agent that you wish on the list.
4. Click Configure Agent Settings for that agent.
5. Scroll down to the bottom of the page.
6. Click Repair Agent Communications.
7. After clicking Repair Agent Communication, the device will take a few seconds to repair and it will give a status update indicating that agent communications were successfully repaired.
8. Then, go back to the Protect tab and Start a Backup.

Once these instructions are done, if the backup is not able to start, please contact Hexistor support so we can do further troubleshooting.