How to Fish Error 51: Fix and Cause

What is How to Fish Error 51?

As of Patch 1.0.10, multiple players report Steam showing “The game How to Fish failed to launch (error code: 51).” At least one player said the game launched normally after purchase and stopped the next day. Another report says the problem appeared after a recent update and survived both file verification and reinstallation.

That evidence confirms the symptom, not a single cause. Steam communities use Error 51 for more than one launch failure, including interrupted content work and access or security conflicts. Without a log, it is not accurate to claim that Error 51 always means antivirus, anti-cheat, or corrupt files.

Which Error 51 fixes should you try in order?

1. Exit Steam completely and restart the computer. Do not only close the library window; use Steam’s Exit command, then launch it again.
2. Finish or cancel pending Steam downloads. Open Downloads and let How to Fish and Steam components settle before retrying. A paused or suspended operation is one possible interpretation of code 51.
3. Confirm the game is on Patch 1.0.10. The current patch writes the version into player.log, which helps distinguish a stale installation from a current-build report.
4. Verify installed files. Open Steam Library → How to Fish → Properties → Installed Files → Verify integrity. This is safe, but current players report mixed results.
5. Remove custom launch options and compatibility settings. Test the normal Steam launch path. Old administrator or Windows compatibility flags can create a different failure rather than solve the original one.
6. Check Windows Security protection history and third-party antivirus quarantine. Restore or allow a file only when it is the official Steam-installed executable. Do not disable all protection for routine play.
7. Reinstall into a clean Steam library folder. Uninstall, confirm the game folder is gone, then reinstall. Back up saves first using the save and progress guide.

If Steam displays the more specific 0x11C7 message instead, use the Smart App Control guide. Error 51 alone does not prove Smart App Control is involved.

What should you avoid?

Do not download replacement executables, cracked launchers, DLL bundles, or registry cleaners. None of the reviewed How to Fish sources support those actions. They add security risk and make a useful bug report harder because the installation no longer matches the Steam build.

Do not repeatedly delete saves. Error 51 happens before the game process starts, so save deletion is not a targeted test. Likewise, changing graphics settings is useful only if the process opens and then crashes. For a red Unity window or immediate desktop crash, use the specific Unity signature guide or the broader crash-on-launch guide.

What information should you collect if it remains broken?

Record the complete Steam message, time of the failure, Windows version, security product, install drive, and whether other Steam games launch. Include player.log only if the game created or updated it; a completely unchanged log suggests the failure occurred before Unity initialized.

The Patch 1.0.10 notes say the version is now printed in player.log for easier debugging. That does not mean the patch fixed Error 51. No official note reviewed here names this code.

Sources

• How to Fish Steam Community hub — current player report stating the game stopped launching with Error 51. Accessed 2026-09-02.
• Steam discussion search: How to Fish Error 51 reports — multiple distinct current reports, including failure after an update. Accessed 2026-09-02.
• Steam Community discussion: general Error 51 troubleshooting — conflicting community explanations and security checks; not game-specific proof. Accessed 2026-09-02.
• Official Steam announcements — Patch 1.0.10 is current and does not list an Error 51 fix. Accessed 2026-09-02.
• Steam user reviews — checked for launch-instability corroboration; exact-code claims come from discussions. Accessed 2026-09-02.