## TL;DR
Fix this in Mode by acting on the exact message first: test the data source connection from the report settings, renew the connection using the saved connection details if the test fails, and rerun the schedule once manually. Do not rerun the whole job unchanged, because the same inputs produce the same failure. Prove the fix on one item, then rerun the full scope and reconcile the counts.

```text
data source connection failed during scheduled run
```

## Use this when
- The operation in Mode fails with this exact message: data source connection failed during scheduled run.
- The same failure repeats on retry with unchanged inputs.
- A review, export or check is blocked until this item completes.

## Not for this skill when
- The message is a permission or 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. That is a quality review, not this failure.

## Steps
1. Reproduce the failure with the smallest scope that still shows it in Mode, and copy the full message plus the item, user or metric involved into the run notes. Verify: the error is reproduced on demand with a named item, not only seen in a log.
2. Apply the specific fix for this error: test the data source connection from the report settings, renew the connection using the saved connection details if the test fails, and rerun the schedule once manually. Verify: the manual run succeeds and the next scheduled run completes.
3. Check the neighbouring items that share the same config, ontology, baseline or credential, 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 Mode 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, decisions or alerts against the source in Mode 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
Scheduled runs use the stored connection; when the warehouse side changes, the stored connection fails only at run time, so the report looks fine in the editor.

## Variant phrasings

### data source connection failed during scheduled run
The verbatim form searchers paste from the terminal or console. Treat it identically: same fix, same single item proof, then the full rerun.

### How to fix: Mode alert failed error "data source connection failed during scheduled run"
The how-to phrasing for the same failure in Mode. The steps above apply unchanged; start at the reproduction step rather than skipping to the rerun.

### Mode 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.

Compatibility: Mode at current versions, plus the platform API or console the query names; no extra tooling beyond a text editor and the source system access needed to verify counts.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_6bV-BpCfBR7MnJvq9e1agw