Changing the account for the DGE service back to the "Local System" account should fix the error. In some scenarios, a connection string needs to be reinitialized using the following steps:
NOTE: It is not recommended to change the account unless this is suggested by One Identity Support. As a first step always try changing the service account back to Local System.
In DGE 6.1.1 and earlier Windows authentication is not supported and the connection string should contain SQL credentials.
1. Run the DGE Server Service under the desired account and restart the service.
2. Go into "HKEY_LOCAL_MACHINE\SOFTWARE\Quest Software\Broadway\Server", backup the key and delete the Q1IMDBConnectionString and QAMAuditActivityDBConnectionString values
3. Run the following cmdlets:
Initialize-QDataGovernanceServer -Databaseconnectionstring 'Data Source=SQLServerName;Initial Catalog=QIMDbName;User ID=sa;Password=passwordForSA;Pooling=False'
Initialize-QDataGovernanceActivity -connectionstring 'Data Source=SQLServerName;Initial Catalog=DataGovernanceActivity;User ID=sa;Password=passwordForSA;Pooling=False'
This will recreate those two keys in the registry encrypted by the new account running DGE server service
4. Restart DGE Server Service.