Snapshots may fail with Reason Maximum allowed active snapshot limit exceeded

Snapshots may fail with "Reason: Maximum allowed active snapshot limit exceeded."

Snapshots may fail with "Reason: Maximum allowed active snapshot limit exceeded."

This means that you have exceeded Amazon's limit of snapshots per account (10000 by default).
The error is "SnapshotLimitExceeded".

You can either limit retention for some of your policies, decreasing the amount of snapshots kept, or ask Amazon to increase the limit.
If you chose to reduce the retention, you will have to delete some snapshots manually, because newly set retention will only affect new snapshots - from now on.

If the limit was exceeded because some policies are "partially successful" and therefore aren't deleting old snapshots - please see https://support.n2ws.com/portal/kb/articles/cpm-doesn-t-delete-snapshots-older-than-the-defined-retention-for-the-policy