What causes a FormatException when parsing numbers in Unity?

float.Parse or int.Parse received a string it cannot read — decimal commas from a player's system culture, stray whitespace or units, or an empty string from a UI field or save file.

How do I catch this when it only happens for some players?

Capture it automatically from the player's device with the full stack trace, the device and OS, the build, and a breadcrumb trail of what they did. That turns a vague complaint into a specific, reproducible issue you can fix without owning the hardware it happens on.

How to Fix “FormatException: Input string was not in a correct format” in Unity

Q: How do you fix a FormatException when parsing numbers in Unity?

Parse with CultureInfo.InvariantCulture, switch to TryParse for anything user- or file-supplied, and write numbers with the invariant culture too so saves round-trip on every locale.

Quick answer: Parse with CultureInfo.InvariantCulture, switch to TryParse for anything user- or file-supplied, and write numbers with the invariant culture too so saves round-trip on every locale.

This crash famously ships fine and then explodes on machines set to German or French locales, where "0.5" and "0,5" swap meanings. Parsing culture is the real bug. Here is the durable fix.

How to fix it

1. Always parse with invariant culture

Replace float.Parse(s) with float.Parse(s, CultureInfo.InvariantCulture) for any string your code wrote — config, saves, network data. The player's OS locale should never affect it.

2. Use TryParse at the boundaries

For UI input and external files, float.TryParse(s, NumberStyles.Float, CultureInfo.InvariantCulture, out var v) turns garbage into a handled branch instead of an exception.

3. Write numbers invariantly too

Symmetry matters: value.ToString(CultureInfo.InvariantCulture) when saving, or a save written on a comma-locale machine will not parse on a dot-locale machine.

4. Reproduce by switching locale

Set your OS region to German (or run with CultureInfo.CurrentCulture = new CultureInfo("de-DE") in a test) to verify the whole save/load path before shipping.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every Unity error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.

A crash you can name from its stack trace is a crash you can usually fix in minutes.