While performing Workflow Infrastructure Configuration, you might face the following exception:
The user account entered for the workflow execution account is not valid. Confirm that the account exists and is enabled.
Please perform the following steps to resolve the issue:
1. Click System administration > Setup > System > System service accounts.
2. Specify the Workflow execution account in the form.
3. Click OK.
Once you have specified the workflow execution account then you should be able to perform the Workflow infrastructure configuration using the wizard.