What causes UserErrorMaxConcurrentRunsLimitReached?

The pipeline's 'Concurrency' setting is too low for the number of simultaneous trigger firings. Multiple overlapping trigger runs are queued while previous runs are still executing. A ForEach activity with high iteration count is creating too many child pipeline runs. Long-running pipeline runs are blocking new runs from starting

How do I fix UserErrorMaxConcurrentRunsLimitReached?

Increase the pipeline concurrency setting: open the pipeline > Settings > Concurrency (default is 1; increase as needed).. Investigate why previous runs are taking longer than expected and optimize them.. If using a tumbling window trigger, enable backfill and retry settings to manage queued runs.. Consider adding a condition to skip new runs if a run is already in progress.. Check ADF Monitor for the oldest running instances and cancel any that are stuck.

Medium severitydata source

Power BI Refresh Error:
UserErrorMaxConcurrentRunsLimitReached

What does this error mean?

An Azure Data Factory pipeline run was rejected because the pipeline already has the maximum number of concurrent runs in progress. ADF enforces a concurrency limit per pipeline to protect downstream systems.

Common causes

1The pipeline's 'Concurrency' setting is too low for the number of simultaneous trigger firings
2Multiple overlapping trigger runs are queued while previous runs are still executing
3A ForEach activity with high iteration count is creating too many child pipeline runs
4Long-running pipeline runs are blocking new runs from starting

How to fix it

1Increase the pipeline concurrency setting: open the pipeline > Settings > Concurrency (default is 1; increase as needed).
2Investigate why previous runs are taking longer than expected and optimize them.
3If using a tumbling window trigger, enable backfill and retry settings to manage queued runs.
4Consider adding a condition to skip new runs if a run is already in progress.
5Check ADF Monitor for the oldest running instances and cancel any that are stuck.

Frequently asked questions

Does this error affect all pipeline runs or just the current one?

Depends on the root cause. A persistent misconfiguration fails every run; a transient issue may resolve on retry. Check the run history.

Can this error appear in Azure Data Factory and Microsoft Fabric pipelines?

Yes — the same connector errors appear in both ADF and Fabric Data Factory pipelines.

How do I see the full error detail for an ADF pipeline failure?

In ADF Monitor, click the failed run, then the failed activity. The detail pane shows the error code, message, and sub-error codes.

Will downstream Power BI datasets be affected when an ADF pipeline fails?

Yes — a dataset refreshing after the pipeline will use stale data or fail if the target table was cleared. The Power BI refresh may succeed while serving wrong data.

Official documentation: https://learn.microsoft.com/en-us/azure/data-factory/data-factory-troubleshoot-guide