Error: Upsert failed. First exception on row 0 with id a0LE000000CU1jYMAT; first error: UNKNOWN_EXCEPTION, The record couldn’t be saved because it failed to trigger a flow. <br>A flow trigger failed to execute the flow with version ID 301E0000000PWMY. <br/> Contact your administrator for help.:  Custom-Post to Inventory - Work Order Usage: WO-00053666. Has anyone else seen an error like this?
Why don't you turn Salesforce.com Logs to see the details of this error message? Viewing Debug Logs
This error is very common if you are trying to upsert data using DataLoader where you have a workflow/ APEX trigger/ Validation rules that stops the records from being updated.
Work on this from Trigger flow ID 301E0000000PWMY and follow the trigger flow to see what caused the record from being upserted.
Kind Regards, Sinan