Studio Assembly Mediation Error
The error com.workday.esb.mediation.MediationException: unable to mediate message at step 'splitter-1'
What it means
A step inside your Studio assembly threw an exception while transforming or routing the message — the assembly itself is fine, but the data flowing through that step wasn't what the step expected (empty payload, wrong structure, or an upstream step that silently produced no output).
Troubleshooting
- Open the integration event's log and find the step name from the error (e.g.
splitter-1) in the assembly. - Inspect the message going into that step — add a write-to-file or log step before it in a test run.
- Common causes: the upstream component returned zero records (empty aggregate), a namespace mismatch in XPath, or an XSLT that emitted nothing.
- Re-run with a known-good small input to separate data problems from assembly problems.
⚡ Quick fix
Guard the failing step with a conditional route that skips it when the payload is empty, or fix the input data and re-launch the integration event.
✓ Permanent fix
Add explicit empty-payload handling and schema/namespace assertions after each transform, plus a try/catch mediation with a human-readable error written to the integration event, so the next failure tells you the cause directly.