Yesterday morning, one of the batch in my company failed with the following error and I had to debug:

The record couldn’t be saved because it failed to trigger a flow.
A flow trigger failed to execute the flow with version ID 200L0000000DApf”

I knew that we do not have any Visual flows hence it should be one of the processes in the process builder failed, but how do I find out the name of the process which has failed?

One of the easiest option is to take the version ID as mentioned above(200L0000000DApf) and go to https://workbench.developerforce.com->Info > Metadata Types & Components.  Click ‘Expand All’ and Search for the ID(200L0000000DApf). You will know the name of the process which has failed and if you want to know in which step it has failed, obviously put a debug log and simulate the scenario to get the error. Then, you can check the log for more information.

Let me know for any questions. Thanks!