[a0123]

How do you fix a bug you can't reproduce?

It's a genuine question because I'm puzzled here.

A very small number of users have this bug (and tbf, it's a really bad bug), and are unable to consistently reproduce it and it seems none of the developers have been able to (the seemingly random nature of the bug occurring is not helping). How is it supposed to be fixed?

[tobias3]

You add more and more diagnostics (e.g. logging) in that area till you manage to track down the bug. Over several years this should be possible. At that point you can either fix the bug directly or do it properly by first reproducing the bug (in a test) and then fixing it.

[inanutshellus]

How do you close a bug you cannot reproduce?

Said another way - If they can't reproduce it, they can't close it.

They may well have fixed it already, but without a way to reproduce it the only prudent behavior is to leave it open and wait for the next diagnostic file to be uploaded.

[justin66]

For starters, put a lot more effort into reproducing it.

[account42]

- You can try harder to reproduce it.

- You can extend logging to gather additional information to reproduce it.

- You can try to reason about the code and figure out possible causes.

- You can attempt to formally verify the correctness of the code.

- You can put guards into the code against unexpected states and actions.

- You can verify the correct result of previous actions before any destructive actions.

- If all fails you can scrap the piece of code in question since it seems to be beyond your ability to maintain.

[ParetoOptimal]

> How do you fix a bug you can't reproduce?

You strangle it from the edges.