English | EN 
On 15 September 2026, La Poste experienced a nationwide IT incident that prevented customers from sending parcels, mailing letters, and purchasing stamps at post offices across France.
The suspected cause? An overnight software update that failed.
Although the issue was resolved later the same day, it serves as a powerful reminder for Quality Engineers, Testers, DevOps Engineers, and Engineering Leaders alike:
The biggest risk is often not the code itself. It’s the change.
What happened?
Customers across France were unable to:
- Send parcels
- Send letters
- Purchase stamps
Meanwhile, online services and banking ATMs remained available.
From a customer perspective, the impact was immediate. For many people, these services are the primary reason for visiting a post office. When they become unavailable, the business is effectively at a standstill.
As quality professionals, we should ask a different question
The first question should not be:
“Who made the mistake?”
Instead, it should be:
“How did a single update become capable of disrupting a national service?”
The goal of quality is not to eliminate all failures. That is unrealistic.
The goal is to ensure failures are small, detectable, recoverable, and ultimately learnable.
Lesson 1: A successful deployment does not guarantee a successful release
One of the most common traps in software delivery is confusing technical success with business success.
The deployment may be green.
The infrastructure may be healthy.
The application may be up and running.
But can customers still achieve their goal?
For La Poste, the critical customer journeys are obvious:
- Send a parcel
- Send a letter
- Purchase a stamp
- Complete a payment
If these journeys are broken, the release has failed regardless of what the deployment dashboard says.
This is why business-focused automated smoke tests are so valuable. They validate what matters most: the customer experience.
Lesson 2: Monitor business outcomes, not just system health
Many teams monitor:
- CPU usage
- Memory consumption
- Response times
- Error rates
These metrics are useful, but they only tell part of the story.
Now imagine monitoring:
- Parcels created per minute
- Letters processed per hour
- Stamp purchases completed
- Successful customer transactions
A sudden drop to zero would immediately reveal that something is wrong, even if the underlying infrastructure appears healthy.
Customers do not care about server metrics.
They care about whether they can complete the task they came to accomplish.
Lesson 3: Reduce the impact when things go wrong
One question worth exploring during a post-incident review is:
Why was the entire country impacted at once?
Modern delivery practices exist specifically to reduce deployment risk:
- Canary releases
- Blue-green deployments
- Progressive regional rollouts
- Feature flags
If a change is first exposed to 5% of users, a problem affects thousands.
If it is exposed to 100% of users immediately, a problem affects millions.
Quality is not only about finding defects before production.
It is also about limiting the consequences when defects inevitably escape.
Lesson 4: Rollback is a product feature
Many organizations invest heavily in deployment automation.
Far fewer invest the same effort in rollback capabilities.
Yet when a release fails, rollback becomes the most valuable feature in the entire system.
Teams should know:
- How to rollback
- Who makes the decision
- How long recovery takes
- Which risks exist during recovery
A rollback procedure that has never been rehearsed is simply a hope disguised as a plan.
Lesson 5: Resilience is part of quality
One interesting aspect of this incident is that not every La Poste service failed.
Online services and banking ATMs remained operational.
This is actually encouraging.
It suggests there was some level of architectural separation between systems.
Good architecture isolates failures.
Great architecture prevents a failure in one domain from cascading into failures everywhere else.
The objective is not to build systems that never fail.
The objective is to build systems that fail gracefully.
Questions I would bring to the retrospective
Rather than focusing on who deployed the update, I would ask:
- Which test could have detected this issue earlier?
- Which monitoring signal was missing?
- Was the rollback fast enough?
- Could the deployment have been more progressive?
- How long were customers impacted before detection?
- What have we learned that will make the next release safer?
The value of a retrospective is not accountability.
Its value is learning.
Final thought
This incident reminds us that software quality extends far beyond testing.
Quality includes:
- Testing
- Deployment strategy
- Monitoring
- Observability
- Recovery mechanisms
- Resilience engineering
Updates will fail.
Integrations will fail.
Systems will fail.
The organizations that earn customer trust are not the ones that never experience incidents.
They are the ones that detect issues quickly, recover rapidly, and continuously improve from what they learn.
Because, in the end, quality is not about avoiding change.
It is about being confident when change happens.
If you were leading the retrospective after this incident, what would be the very first question you would ask the team?