Workflow only successfully running, about 1 in every 10 times I trigger it. Any thoughts and ideas at all would be much apreciated

Question

I have a SPD 2010 work flow, that is triggered when a user uploads a document to a library.

The workflow itself is pretty simple.

It updates a field in another list by doing look up on a field in the document being uploaded, and finding a matching record to be updated in the target list.

Its one action long, and should not be problematic.

And I have gone to great lengths to ensure that its not some kind of coercion error brought on by the look up.

Moreover I believe I can logically eliminate the workflow structure and logic itself as the source of the problem, since the workflow has and will run successfully.

The problem is that, although it has run successfully, it only does so rarely.

Most of the time I trigger the workflow, it cancels immediately. Logging only the following error.

Coercion Failed: Unable to transform the input lookup data into the requested type.

and not any of the history logging errors I have placed before and after the action in an attempt to troubleshoot. Which suggests to me that the problem does not lie within the workflow, rather the workflow itself is just failing to run at all.

Any thoughts ideas or even just keywords to google would be a huge help.

Thanks in advance.

Here's the work flow:

Step 1

 Update item in Document Library A

Here's how the look up is configured.

 In  Document Library A

 Where Doc ID Value == Current Item Attached To (Which is a Field which contains Doc ID as a Look Up Value(Text) )

Answer 1

When performing a lookup on a metadata field associated with document, I always added a "Pause for Duration" action of 5 minutes at the start of the workflow. Reason being, uploading a document with metadata is a 2 step process. First, the document is uploaded. Second, the metadata is submitted after the document is uploaded. The problem is that the workflow will trigger once the document is uploaded, and the metadata typically isn't available. By adding the Pause for Duration at the start of the workflow, your action to match the lookup values should start functioning consistently.