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Rockwell backup failure: "invalid class string"

Rockwell DeviceLink backups whose error logs contain "invalid class string" often fail due to the correct version of Studio 5000 being missing on the Agent

If your Rockwell DeviceLink backup is failing and contains an error line like the one seen below, you may just need to install the requisite version of Studio 5000. You can confirm this by attempting to manually upload from the device on the Agent.

Unhandled Exception: System.Runtime.InteropServices.COMException (0x800401F3): Invalid class string (Exception from HRESULT: 0x800401F3 (CO_E_CLASSSTRING))

The Agent computer must have all required IDEs installed in order to perform a backup. For example, if you have attempting to back up an Allen-Bradley PLC that is running firmware V24, but you only have Studio 5000 V35 installed on the Agent, the backup will fail. You would need to install Studio 5000 V24 on the Agent computer as well.