# FMOD Studio: Encounterd Error: ERR\_HEADER\_MISMATCH There is a version mismatch between the FMOD header and either the FMOD Studio library or the FMOD Low Level library **URL:** \ **Category:** Unity\ **Tags:** unity\ **Created:** [November 11, 2021, 1:03am UTC](https://qa.fmod.com/t/fmod-studio-encounterd-error-err-header-mismatch-there-is-a-version-mismatch-between-the-fmod-header-and-either-the-fmod-studio-library-or-the-fmod-low-level-library/17937 "2021-11-11T01:03:30Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![LutherP](https://avatars.discourse-cdn.com/v4/letter/l/3bc359/32.png) [@LutherP](https://qa.fmod.com/u/LutherP)\ **Post date:** [November 11, 2021, 1:03am UTC](https://qa.fmod.com/t/fmod-studio-encounterd-error-err-header-mismatch-there-is-a-version-mismatch-between-the-fmod-header-and-either-the-fmod-studio-library-or-the-fmod-low-level-library/17937/1 "2021-11-11T01:03:30Z")
Hi there, For context: - I’m using Unity 2021.1.13f1 - I recently updated to FMOD 2.01.11 Had to update our version of FMOD and immediately ran into this error: FMOD Studio: Encounterd Error: ERR\_HEADER\_MISMATCH There is a version mismatch between the FMOD header and either the FMOD Studio library or the FMOD Low Level library. UnityEngine.Debug:LogError (object) FMODUnity.EditorUtils:CheckResult (FMOD.RESULT) (at Assets/Plugins/FMOD/src/Editor/EditorUtils.cs:36) FMODUnity.EditorUtils:CreateSystem () (at Assets/Plugins/FMOD/src/Editor/EditorUtils.cs:263) FMODUnity.EditorUtils:get\_System () (at Assets/Plugins/FMOD/src/Editor/EditorUtils.cs:338) FMODUnity.EventManager:UpdateCache () (at Assets/Plugins/FMOD/src/Editor/EventManager.cs:144) FMODUnity.EventManager:RefreshBanks () (at Assets/Plugins/FMOD/src/Editor/EventManager.cs:30) FMODUnity.EventManager:Startup () (at Assets/Plugins/FMOD/src/Editor/EventManager.cs:486) UnityEditor.EditorApplication:Internal\_CallDelayFunctions () It looks like something didn’t update since I imported the package downloaded from FMOD, but no matter how many times I attempt to reinstall the FMOD package, it doesn’t make a difference. I’ve even tried nuking all of my files and redownloading the whole project from Unity Hub, but to no avail. Other symptoms include: - FMOD not showing up in the package manager - Clicking ‘FMOD \> About Integration’ displays my version of FMOD as ‘Version 0.00.00’ The only relevant post I can find [is this one](https://qa.fmod.com/t/unity-2019-1-12-updating-project-to-fmod2-error-err-header-mismatch/15313), and the user never listed their resolution steps, as they didn’t know what they were either. Any help would be greatly appreciated. ---
**Author:** ![alexzzen](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/alexzzen/32/6825_2.png) [@alexzzen](https://qa.fmod.com/u/alexzzen)\ **Post date:** [November 11, 2021, 10:26am UTC](https://qa.fmod.com/t/fmod-studio-encounterd-error-err-header-mismatch-there-is-a-version-mismatch-between-the-fmod-header-and-either-the-fmod-studio-library-or-the-fmod-low-level-library/17937/2 "2021-11-11T10:26:17Z")
just delete everything FMOD related from your project while the Unity app is closed and then import the package again. ---
**Author:** ![LutherP](https://avatars.discourse-cdn.com/v4/letter/l/3bc359/32.png) [@LutherP](https://qa.fmod.com/u/LutherP)\ **Post date:** [November 11, 2021, 11:22pm UTC](https://qa.fmod.com/t/fmod-studio-encounterd-error-err-header-mismatch-there-is-a-version-mismatch-between-the-fmod-header-and-either-the-fmod-studio-library-or-the-fmod-low-level-library/17937/3 "2021-11-11T23:22:45Z")
What’s the best way for me to find everything FMOD related? I tried deleting every file and folder with FMOD in its name while Unity was closed, then reimporting, but that didn’t seem to work. ---
**Author:** ![jeff\_fmod](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/jeff_fmod/32/1766_2.png) [@jeff\_fmod](https://qa.fmod.com/u/jeff_fmod)\ **Post date:** [November 15, 2021, 5:36am UTC](https://qa.fmod.com/t/fmod-studio-encounterd-error-err-header-mismatch-there-is-a-version-mismatch-between-the-fmod-header-and-either-the-fmod-studio-library-or-the-fmod-low-level-library/17937/4 "2021-11-15T05:36:40Z")
Usually deleting everything under Assets/Plugins/FMOD and reinstalling should get it back to a good state. This definitely sounds like a bug though, can you please let me know what version of FMOD you had before updating so I can try reproducing? ---
**Author:** ![LutherP](https://avatars.discourse-cdn.com/v4/letter/l/3bc359/32.png) [@LutherP](https://qa.fmod.com/u/LutherP)\ **Post date:** [November 15, 2021, 7:03pm UTC](https://qa.fmod.com/t/fmod-studio-encounterd-error-err-header-mismatch-there-is-a-version-mismatch-between-the-fmod-header-and-either-the-fmod-studio-library-or-the-fmod-low-level-library/17937/5 "2021-11-15T19:03:53Z")
Our original version of FMOD was Studio.01.10.00. We had to update because we’re working on a Nintendo Switch Port, so we can’t step our version backwards to eliminate the issue. This only appears to happen in the Windows version of Unity, while the Mac version is stable. Unfortunately, the Nintendo SDK only work with Windows machines, hence the problem. ---
**Author:** ![jeff\_fmod](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/jeff_fmod/32/1766_2.png) [@jeff\_fmod](https://qa.fmod.com/u/jeff_fmod)\ **Post date:** [November 16, 2021, 12:44am UTC](https://qa.fmod.com/t/fmod-studio-encounterd-error-err-header-mismatch-there-is-a-version-mismatch-between-the-fmod-header-and-either-the-fmod-studio-library-or-the-fmod-low-level-library/17937/6 "2021-11-16T00:44:59Z")
In that case there are some additional steps when [updating from 1.10](https://fmod.com/resources/documentation-unity?version=2.02&page=user-guide.html#upgrading-from-110). Can you please try getting your 1.10 files back in, updating the plugin to 2.01.11, and finally moving everything from Assets/Plugins/Editor/FMOD to Assets/Plugins/FMOD/src/Editor?