App is buggy: how to find the cause and fix it without rebuilding
The app crashes, doesn't save data or broke after an update, and the developer who built it is gone. People often think everything has to be rewritten from scratch. In reality most bugs can be fixed in place once you find the cause.
Collect the facts first
"The app doesn't work" won't help anyone find a bug. Write down:
- What exactly happens: it crashes, freezes, shows an error, doesn't save data.
- When it started: after an app, phone or server update, or for no visible reason.
- Who is affected: all users or only certain phones (Android or iPhone, older OS versions).
- How to reproduce: step by step, what to tap to make the error appear.
- A screenshot or video of the error.
This is often enough to narrow the search down to one part of the code.
The most common causes
1. A system or service the app depends on was updated
A new Android or iOS version, changes in a payment system, maps or Google sign-in. The app's code didn't change, but the world around it did. Fix: update the libraries and adjust the code to the new requirements.
2. The server doesn't respond the way the app expects
The server address changed, the SSL certificate or hosting expired. The app can't get data, so the screen is empty or the app crashes.
3. A bug in a new feature
Something new was added and something old broke. Comparing code versions helps: what exactly changed between the working and the broken version.
4. Data the developer didn't expect
A long title, an empty field, unusual characters, a huge image. The app doesn't know what to do with it and crashes.
What to prepare for the fix
- Access to the code: a repository (GitHub, GitLab) or a project archive.
- Access to the server and services the app uses. Better as a separate user, not your own password.
- Access to the store consoles (Google Play Console, App Store Connect) if an update has to be released.
- The bug description from the first section.
Don't hand over your main passwords. Almost every service lets you add another user with limited rights, and you can delete it after the work.
When a rewrite really makes sense
Rewriting from scratch makes sense if the code uses technology that's no longer supported, if every fix breaks something else, or if the app has to change completely for a new business. In other cases a focused fix and improvements cost many times less and are much faster.
I set up Google Shopping, Google Ads and SEO for online stores and small businesses. I write in plain language, no fluff. If something from this article doesn't work for you, message me and I'll help.
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