Check Last Non-Scheduled Build For Error
If you notice that scheduled workflows that were previously triggered according to the schedule specified in your
config.yml suddenly stopped running, you'll need to check the last non-scheduled build attempt on the related branch (triggered by a push, a pull-request, or via the CircleCI API).
If that build attempt resulted in a
Build Error failure due to a
Config Processing Error (which happens if the configuration file is invalid), then all currently scheduled workflows will get unscheduled.
To restore the schedule you'll need to trigger a new build (with a valid configuration file) on the related branch.
Gap in the Scheduled Workflow Runs
In case you see a gap in the scheduled workflow runs (e.g. if they stopped running for a period of time, and then started running again), this means that at some point a build was triggered with an invalid configuration file which caused the situation described above.
Then another build was subsequently triggered with a valid configuration file, and the schedule was restored.
Note: In an effort to provide more flexibility and control we have launched Scheduled Pipelines, with the ability to schedule your pipelines to run via the Project Settings or the API, which you can read more about here: