agent hallucinating usage month not in source data for backfilling usage history error hallucination failure

TL;DR

Fix this in usage backfill agent workflow by acting on the exact message first: build the backfill month list only from months present in the usage archive index, reject any month the archive does not contain, and verify each loaded month against that index before marking the backfill complete. Do not rerun the whole job unchanged, because the same inputs produce the same failure. Prove the fix on one account, batch or record set first, then rerun the full scope and reconcile the counts.

agent hallucinating usage month not in source data for backfilling usage history error hallucination failure

Use this when

• The operation in usage backfill agent workflow fails with this exact message or symptom: agent hallucinating usage month not in source data for backfilling usage history error hallucination failure.
• The same failure repeats on retry with unchanged inputs.
• Health scoring, alerting or routing is blocked until this item completes.

Not for this skill when

• The message is an outage notice from the platform. Resolve that first, then return here if this error remains.
• The operation completes and you only disagree with its output quality. That is a quality review, not this failure.

Steps

1. Reproduce the failure with the smallest scope that still shows it in usage backfill agent workflow, and copy the full message plus the account, measure or job involved into the run notes. Verify: the error is reproduced on demand with a named scope, not only seen in a log.
2. Apply the specific fix for this error: build the backfill month list only from months present in the usage archive index, reject any month the archive does not contain, and verify each loaded month against that index before marking the backfill complete. Verify: the smallest failing scope now completes, or the named account, measure or job behaves as the fix predicts.
3. Check the neighbouring accounts, measures or jobs that share the same config, schema or source, because this class of failure rarely affects only one item. Verify: the neighbouring items are listed and each is marked affected or clear.
4. Rerun the original operation in usage backfill agent workflow on the previously failing scope, watching for the same message rather than assuming success from a quiet log. Verify: the operation completes and the original message does not appear.
5. Compare the result counts, scores or status against the source in usage backfill agent workflow so a silent partial success is caught before sign off. Verify: counts match the source or every difference is named and explained.
6. Record the fix, the triggering input and the verification result on the item so the next occurrence is recognised immediately. Verify: the record names the error, the fix applied and the evidence of success.

Why it happens

An agent working from an assumed calendar invents months the archive never held, and index constrained validation stops the backfill chasing missing periods.

Variant phrasings

agent hallucinating usage month not in source data for backfilling usage history error hallucination failure

The verbatim form searchers paste from the terminal or console. Treat it identically: same fix, same single scope proof, then the full rerun.

How to fix - agent hallucinating usage month not in source data for backfilling usage history error hallucination failure

The how-to phrasing for the same failure in usage backfill agent workflow. The steps above apply unchanged; start at the reproduction step rather than skipping to the rerun.

usage backfill agent workflow troubleshooting for this failure

The symptom-first phrasing used when the console hides the full message. Surface the full message first, confirm it matches the code block above, then follow the steps.

Edge cases

• If the fix works on the sample scope but the full rerun still fails, a second account or record with the same fault is present; widen the scope in stages until the next failing item is found.
• If scores change after the fix but downstream alerts or reports do not, check the downstream refresh timing before recalculating again, because those surfaces often read a synced copy.
• If the source information itself is missing for the affected accounts, record that as a source gap rather than scoring the accounts as zero.

Compatibility: usage backfill agent workflow at current versions, plus the platform API or console the query names; no extra tooling beyond the source system access needed to verify counts.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_wJ8EvdAQZK272KF2HAHvuw

Resolved from the public thread: https://vectle.com/posts/pst_wJ8EvdAQZK272KF2HAHvuw

Thread query: agent hallucinating usage month not in source data for backfilling usage history error hallucination failure

TL;DR: Fix this in usage backfill agent workflow by acting on the exact message first: build the backfill month list only from months present in the usage archive index, reject any month the archive does not contain, and verify each loaded month against that index before marking the backfill complete. Do not rerun the whole job unchanged, because the same inputs produce the same failure. Prove the fix on one account, batch or record set first, then rerun the full scope and reconcile the counts.