Quick answer: Determine whether it is an incomplete fix, a masked symptom, or a fresh regression, then fix the actual root cause and verify with version-tagged data that it truly stopped. A bug that keeps returning is telling you your previous fix treated the symptom, not the cause, find the cause and confirm it with data this time.
Few things are more demoralizing than a bug you fixed reappearing, sometimes more than once. A recurring bug is a signal that something about your previous fix was incomplete: it addressed a symptom rather than the cause, missed some cases, or the underlying problem got reintroduced. Breaking the cycle means diagnosing why it keeps coming back, fixing the true root cause, and then verifying with real data that it has actually stopped this time, not just on your machine.
Diagnose Why It Returned
A recurring bug comes back for one of a few reasons, and the fix depends on which. It may be an incomplete fix that resolved the case you tested but not the variants players hit. It may be a masked symptom, where you fixed the visible effect while the underlying cause kept producing it in new forms. Or it may be a genuine regression, where a later change reintroduced the original problem. Identifying which of these you are dealing with is the first step, because each needs a different response.
The history matters here. Bugnet keeps the issue's full record, its original reproduction, every occurrence, and the versions it has appeared in, so when a fixed bug returns you can see whether it is the exact same manifestation (likely a regression or incomplete fix) or a new variant (likely a masked symptom). That history is what lets you diagnose the recurrence instead of just re-fixing it the same way that already failed.
Fix the Root Cause, Not the Symptom
The reason a bug keeps coming back is almost always that previous fixes treated symptoms. A crash patched by catching the exception still has the underlying bad state causing it; a visual glitch patched by hiding the artifact still has the rendering error producing it. To break the cycle you have to go deeper than before, to the actual root cause, and fix that, even though it is more work than another symptom patch.
Use the accumulated occurrence data to understand the bug's full shape before fixing it again. The variants, the conditions, the hardware, all the context across every occurrence often reveal the common root that the earlier narrow fixes missed. Fixing that root is what finally stops the recurrence, where each prior symptom-level fix only delayed it.
Verify With Data and Guard Against Regression
This time, do not trust that it is fixed, prove it. After shipping the root-cause fix, watch the issue's occurrence count on the new version: it should go to zero and stay there. A recurring bug has already fooled you once by seeming fixed, so the bar for declaring it done is real-world data showing it stopped, not your local testing showing it does not reproduce.
Then guard against it returning yet again. For a bug that has come back before, it is worth a permanent regression check, a test or a documented repro you re-verify, so a future change cannot quietly reintroduce it a third time. Combine root-cause fixing, version-tagged verification, and a regression guard, and you convert a frustrating recurring bug into one that is genuinely, finally closed, instead of one more entry in the cycle of fix-and-return.
A bug that keeps returning was never really fixed. Find the root cause, verify with data, and guard it so it can't come back.