Fivetran: Some MNTN Connections Are Failing With 400 INCOMPATIBLE_TABLE_COMBINATION Errors

This incident has been resolved. We have observed that instance rates are returning to normal levels and affected connectors are syncing successfully.

Incident Summary
Description:
We identified an issue for the mountain connector, which resulted in syncs failing with a 400 INCOMPATIBLE_TABLE_COMBINATION error.

Timeline:
This issue began on September 25 at 6:30 PM UTC and was resolved on September 26 at 1:50 AM UTC.

Cause:
Connectors started to fail because `api3.mountain.com/apidata` has started rejecting requests that combine `graph.*` fields with `SegmentInfo.*` fields due to a deprecation of query parameters on the source side.

Resolution:
Fivetran implemented a skip-on-failure mechanism to bypass 400  errors and allow syncs to proceed. We have also reached out to the source team to investigate the underlying issue and are currently waiting for their response.

We have deployed a fix for this issue by skipping the affected endpoints with a dashboard warning.
We will continue to monitor all affected connectors until they resume their normal sync functionality.

Next Expected Update: 3 hours

We're working on a change to skip the affected endpoints with a dashboard warning. This will allow other endpoints to continue syncing while the underlying issue is resolved.

We've also reached out to the MNTN team to validate the issue and resolution approach.

We've identified an issue affecting approximately 37% of MNTN connections. They're failing because `api3.mountain.com/apidata` has started rejecting requests that combine `graph.*` fields with `SegmentInfo.*` fields. This appears to be because of a deprecation of functionality on the source API. Our engineers are investigating.