Support & troubleshooting
Bug fixing: we repair what no longer works
Bug fixing means identifying, reproducing and correcting a defect in an existing application or website, then verifying that the fix does not break something else. Agencei works on code we did not write: React or Angular web apps, React Native mobile apps, Node.js, Java or Python backends, WordPress sites and PrestaShop stores.
This service is for businesses facing an annoying or blocking bug that lack the skills, time or original provider to deal with it. It may be a form that no longer submits, a payment that fails, a random 500 error, an incorrect calculation or a mobile app that crashes on launch.
Our approach is methodical: we do not patch a symptom, we trace it back to the cause. Error logs, tracking tools such as Sentry, debuggers, reproduction tests in a staging environment: every fix is explained, tested and delivered with regression tests whenever the project allows it.
When do we step in?
Blocking bug in production
An essential feature is down: orders cannot be placed, logins are refused, an export fails. We step in quickly to restore service, then address the underlying cause.
Intermittent error that cannot be reproduced
The problem appears for some users, at certain times, with no obvious logic. We put in place the logging and error tracking needed to capture it, then reproduce it.
Regression after an update
A framework, WordPress plugin, PrestaShop module or operating system update broke behaviour that used to work. We identify the responsible change and apply the appropriate fix.
Original provider unavailable
The developer who knew the code is gone. We take over the project, set up a test environment and fix things without depending on someone else's memory.
Backlog of accumulated bugs
Your application works but carries dozens of small defects reported by users. We qualify them, prioritise them and handle them in batches with controlled releases.
How we work
- 1
Qualifying the bug
We gather concrete elements: steps to reproduce, screenshots, affected accounts, browser or app version, date it first appeared, recent changes. This step avoids looking in the wrong place.
- 2
Reproduction in a test environment
We reproduce the problem on a staging environment or locally, from an anonymised copy of the data if needed. A reproducible bug is a bug that is half fixed.
- 3
Root cause analysis
Reading application and server logs, Sentry traces, SQL queries, third-party API calls, step-by-step debugging. We separate the real cause from side effects and document what we find.
- 4
Fix and tests
The fix is written as close to the cause as possible, accompanied by an automated test when the project allows it, and checked on neighbouring cases to avoid any regression.
- 5
Controlled deployment
Release to production following your process (branch, review, CI/CD, prior backup), with a rollback plan. We watch logs and error tracking after delivery.
- 6
Report
You receive a clear explanation: what was happening, why, what was changed and what we recommend to prevent the problem from coming back.
Technologies we use
- Sentry and error tracking
- Chrome DevTools
- Xdebug and Node.js / Java debuggers
- Jest, Vitest and JUnit
- Playwright and Cypress
- Postman
- Nginx, Apache and PHP-FPM logs
- Query Monitor (WordPress)
- PrestaShop debug mode
- Git and GitLab CI
- Docker (reproduction environments)
Related expertise
Why choose Agencei?
We look for the cause, not just the symptom
A quick workaround can hide a problem that will come back later in another form. We always explain the origin of the bug and propose the lasting fix.
Broad technical coverage
Frontend, backend, mobile, database, CMS: we can read a React stack trace as easily as a Java exception or a PHP log. You do not need to find a specialist for each layer.
Releases that do not break things
Every fix goes through a test environment, a review and a rollback plan. We never modify production directly without a backup.
Concrete communication
No unnecessary jargon: you know what we found, what we changed and how long it took.
In brief
- What is this service?
- Agencei bug fixing is an intervention service on existing applications and websites to reproduce, diagnose and correct a defect, with regression tests and controlled deployment.
- Who is it for?
- It is aimed at businesses whose web app, mobile app, API, WordPress site or PrestaShop store has a defect and who lack the in-house skills or the original provider to deal with it.
- What problem does it solve?
- A bug blocks a feature, drives users away or corrupts data, and nobody knows where it comes from. The service provides a diagnosis based on logs and tracking tools, then a lasting fix.
- How long does it usually take?
- A well-described bug is often fixed in a few hours. An intermittent problem, a complex regression or taking over undocumented code can take several days.
- What factors influence the price?
- The price depends on the complexity of the bug, the quality and documentation of the existing code, the presence of a test environment, the number of bugs to handle and the urgency.
- How does the engagement run?
- Qualification, reproduction in a test environment, root cause analysis from logs and traces, fix with tests, controlled deployment with rollback available, report.
- What are the risks?
- Fixing a symptom without understanding the cause makes the problem come back. Changing production without a backup or tests can create a regression worse than the original bug.
- What alternatives exist?
- Having the original provider fix it if available, working around the problem through configuration, or considering a rebuild if the application accumulates too many structural defects.
Frequently asked questions
How long does it take to fix a bug?
It depends on its complexity and on the quality of the existing code. A well-described, easily reproducible bug is often resolved in a few hours. An intermittent problem or one tied to a fragile architecture may require several days of diagnosis. We give an estimate after qualification.
What if the bug cannot be reproduced?
We add targeted logging and an error tracking tool such as Sentry to capture the exact context at the moment the problem occurs. Once the data has been collected, reproduction becomes possible and the fix follows.
Do you work on WordPress or PrestaShop sites?
Yes. CMS bugs often come from a plugin or module conflict, a modified theme or a PHP update. We use the debugging tools specific to each platform and fix things in a way that does not block future updates.
Can you fix a bug without access to the source code?
Rarely. For a clean fix, we need the source code and ideally the Git repository. Without it, we can sometimes work around the problem at server or configuration level, but that is not a lasting solution and we will tell you so.
How is bug fixing billed?
Most often on time spent, with an estimate after qualification. For simple bugs, a fixed price is possible. The cost depends on complexity, the quality of the existing code and whether a test environment exists.
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Tell us about your project
Describe your need in a few lines: we come back to you with a first analysis and the next steps.