Bug testing gets easier when the team has a shared language for what can go wrong.
Not every issue belongs in the same bucket. A broken checkout flow, a confusing menu, an invalid date field, and a misaligned button all affect quality, but they usually need different owners and different fixes. Categorizing bugs helps QA, support, product, and engineering triage issues faster.
Here are five practical bug types to keep in mind while testing a SaaS product.
Functional bugs
Functional bugs happen when a feature does not do what it is supposed to do.
Examples include:
- A login button that does nothing
- A user being routed to the wrong account
- A payment status not updating after checkout
- A notification being sent to the wrong audience
- A report exporting incomplete data
Functional bugs are often high priority because they block the user’s goal. When reporting them, describe the expected behavior and the actual behavior clearly. If the bug affects customer data, permissions, billing, or security, include that impact in the report.
UI and navigation bugs
UI and navigation bugs make the product harder to move through, even if the underlying feature still works.
Examples include:
- A menu item leading to the wrong page
- A modal that cannot be closed on mobile
- A back button that loses the user’s progress
- A tab order that makes keyboard navigation difficult
- A link label that does not match the destination
These issues often look small, but they add friction quickly. In support-heavy products, poor navigation also creates more “where do I find this?” tickets. If your team uses live chat, repeated navigation questions are a useful signal that the interface needs attention.
Input validation bugs
Input bugs happen when the product accepts, rejects, stores, or transforms user-entered data incorrectly.
Examples include:
- Required fields allowing empty values
- Email fields accepting invalid addresses
- Date fields failing with certain time zones
- Numeric fields accepting negative values where they should not
- Forms showing unclear errors after submission
Good input testing includes normal cases, edge cases, and invalid cases. Test long names, special characters, copied text, browser autofill, different locales, and values at the minimum or maximum limit.
System and environment bugs
Some bugs only appear under specific technical conditions. They may depend on browser, device, operating system, network quality, app version, extensions, memory, or permissions.
Examples include:
- A page freezing on older mobile devices
- A feature failing in one browser but not another
- Uploads breaking on slow connections
- Push notifications failing after an OS permission change
- A customer seeing stale data after switching tabs
These bugs are hard to reproduce without context. A visual report with device details, browser version, session steps, and console logs is far more useful than a plain text description. Gleap’s in-app bug reporting is designed for exactly this kind of evidence capture.
Visual bugs
Visual bugs affect how the product looks. They may not break a workflow, but they can damage trust, accessibility, and perceived quality.
Examples include:
- Misaligned buttons or icons
- Text overlapping on smaller screens
- Incorrect colors or font weights
- Layout shifts after loading
- Dark mode contrast problems
- Broken images or missing empty states
Visual testing matters most before launch, after design system changes, and on high-traffic pages such as onboarding, checkout, dashboards, and support widgets.
Turn bug categories into better reports
Bug categories are useful only if they lead to better action. A strong bug report should include:
- What the tester expected to happen
- What actually happened
- Steps to reproduce the issue
- Screenshots or recordings
- Browser, device, and app version
- Console logs or network errors when available
- Severity and customer impact
The goal is not to write longer reports. It is to remove guesswork. When teams capture the right evidence at the moment the issue happens, developers can reproduce problems faster and product teams can see which categories are creating the most friction.