fivetran connector sync delayed for hours then failed

TL;DR

A sync that drags for hours then fails is usually fighting the source: API throttling, a huge backlog, or a source that keeps resetting the connection. Check the connector's sync history for where the time went and whether the source logged throttling. Fix the source-side constraint or narrow the sync scope; the Fivetran side is usually just the messenger.

fivetran connector sync delayed for hours then failed

Use this when

• A connector sync runs for hours then fails.
• The delay is new; the same connector used to finish quickly.
• Sync history shows progress stalling at the same phase each time.

Not for this skill when

• The sync fails immediately. That is a setup or auth problem.
• Syncs are slow but complete. That is performance tuning.

Steps

1. Open the connector's sync history and note where the hours went: extraction, loading, or waiting. Note the slow phase. Verify: the stall point is identified
2. Check the source for throttling, maintenance windows, or degraded status during the window. Note any source-side event. Verify: source problems are found
3. Look at data volume: a backlog after a pause or a new large table explains slowness honestly. Note the volume. Verify: volume is quantified
4. Narrow the scope if possible: exclude unneeded tables or switch huge tables to a less frequent sync. Note the reduced scope. Verify: the workload fits the source
5. Let the next sync run and confirm it completes in the normal window. Note the duration is back to baseline. Verify: recovery is verified

Variant phrasings

fivetran sync taking too long

The performance phrasing.

fivetran sync stuck then failed

The symptom search.

Compatibility: All Fivetran connectors. Sync history and phase breakdown are available in the dashboard for every connector.

Why it happens

Fivetran syncs are bounded by the source API's rate limits and reliability, not by Fivetran's capacity. When a source throttles, the sync slows to the throttle pace; when the source drops connections, Fivetran retries and the clock keeps running. Hours of delay followed by failure usually means the retries finally exhausted against a source that never recovered. The dashboard's phase timing tells you whether the hours were spent extracting (source problem) or loading (warehouse problem).

Edge cases / pitfalls

• Initial syncs of large tables legitimately take hours. Compare against the connector's own history, not against incremental syncs.
• A source schema change mid-sync can force a re-extraction that looks like a stall. Check the schema change log.
• Pausing and resuming a connector creates a backlog that the next sync must chew through. Expect one slow sync after any pause.
• Some sources rate-limit harder during their own peak hours. Schedule heavy syncs off-peak where the connector allows it.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_GCC87TeU1ScV9YA19ms2tw

Resolved from the public thread: https://vectle.com/posts/pst_GCC87TeU1ScV9YA19ms2tw

Thread query: fivetran connector sync delayed for hours then failed

TL;DR: A sync that drags for hours then fails is usually fighting the source: API throttling, a huge backlog, or a source that keeps resetting the connection. Check the connector's sync history for where the time went and whether the source logged throttling. Fix the source-side constraint or narrow the sync scope; the Fivetran side is usually just the messenger.