Definition
What is a silent failure?
A silent failure is an automated job that reports success but did not do its work. It ran and processed nothing, or it never started at all. No error is raised, so monitoring that watches for errors never sees it, and it carries on until an auditor, a regulator or a customer notices.
Why monitoring misses it
Monitoring alerts you when something throws an error. A job that never starts throws nothing. A job that runs and processes zero records finishes successfully.
So the dashboard stays green. Green only ever meant that no errors were raised, which is not the same claim as the work having happened.
The two checks that catch it
- Expected-run check
- Confirms that a job ran when it was supposed to. A run that never happened raises no error, so the only way to see it is to know when it should have run and look for it.
- Expected-output check
- Confirms that a run produced what it should have: records written, a receipt returned, rows deleted. A job can finish successfully having done nothing at all.
Where it costs the most
Regulated obligations, where the system's own status is not evidence that the obligation was met.
| Obligation | What the system reports | What shows it happened |
|---|---|---|
| VAT return (Making Tax Digital) | Submission job completed | A receipt back from HMRC for every quarter's return |
| E-invoicing (KSeF, Poland) | Invoice sent | A KSeF number assigned to every invoice |
| Company tax and accounts (CT600, Companies House) | Filing job succeeded | An acceptance from HMRC or Companies House, not only a submission |
| GDPR retention and erasure | Nightly deletion job: success | Records actually deleted, matching what was due |
| Data pipelines and syncs | Scenario completed | Records arriving where they should, in the expected range |
Questions
Silent failure, briefly.
Is a silent failure the same as a bug?
Not quite. A bug usually produces something wrong that someone eventually sees. A silent failure produces nothing, and reports that it succeeded, so nobody is looking for it.
How do I know if I have one?
Pick one job that matters and ask how you would find out, today, if it had stopped running. If the honest answer is that someone downstream would eventually notice, you cannot currently tell.
What does it cost to check properly?
The Silent Failure Audit is £1,500 for one process area or £3,000 for a full sweep, fixed. Five working days, read-only access, and a written report on which of your automated jobs actually ran.