> For the complete documentation index, see [llms.txt](https://docs.coherence.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.coherence.io/0.10/overview/troubleshooting.md).
# Known Issues and Troubleshooting
### Baking fails under Ubuntu 22.04
Ubuntu 22.04 suffers from a GLIBC version mismatch, resulting in **coherence** baking failure. The current solution is to downgrade by one version of Ubuntu.
### Sample UI behaves/looks odd after upgrading
Revert all your Prefab Instance Overrides
Overrides popup for the Sample UI Prefab Instance
### I can't see other players' rooms
Check that all your clients are using the same Schema ID.
Schema ID in coherence Hub (Baking section)
### Can't build on platforms that Unity Hub reports as installed
On macOS, some versions of the Unity Hub don't install platform modules properly. This issue is fixed on version Unity Hub version 3.3.0. If you want to use a prior version, **install one module at a time**.
### BuildConfiguration assets missing defining script
SDK 0.9 release removed dependency to the experimental package Platforms. As a result, your existing BuildConfiguration assets will have its defining script missing. To recreate the Simulator build configuration with the new pipeline, you can do it from the Simulators Module in coherence Hub.
### Multi-scene setup
When networked Entities are added by loading a scene additively, mind that the `CoherenceMonoBridge` must be set to a *singleton mode*. In case of a non-singleton *MonoBridge* the Entity will search for a *MonoBridge* instance within its scene, and if none is found it will be created in that scene. This applies to both `CoherenceSync` and `LiveQuery` objects.
For a complete control over `CoherenceMonoBridge` resolving you can use either `CoherenceSync.MonoBridgeResolve` instance event or `MonoBridgeStore.MonoBridgeResolve` global event. A `CoherenceMonoBridge` instance provided by the `MonoBridgeResolve` event takes precedence over the scene and singleton ones.
### Showing incorrect SDK version
Sometimes the package cache gets stalled and after updating the **coherence** package you might find Unity still uses the old package version. Try `Reimport all` or closing the project, deleting the `Library` folder, and reopening the project again. It will clean and update packages cache, and use the version of **coherence** stated in `manifest.json`.
### Type '...' already defines member called '...' with the same parameters
Currently, coherence doesn't support networking prefabs with the same name. Doing so can yield duplicated definition errors. Best course of action is to rename your prefabs so they have different names.
We will support networking prefabs with the same name in the future.
If you have issues building Clients or Simulators, refer to [troubleshooting](/0.10/overview/troubleshooting.md).
### **Prefab Variants using excessive memory**
When working with Prefab Variants, Unity leaks managed references (fields marked with `[SerializeReference]`). This can make your prefab grow big and use more memory than necessary. Until Unity fixes this issue, we provide you with the ability to **prune** the leaked references. Pruning is only available for Unity 2021.2+.
### **Building for WebGL**
Unity does not build WebGL because Python 2 is missing on latest macOS and Ubuntu 22. This is fixed on Unity 2020.3.40f1 and onwards.
Dots (`.`) are not supported as part of WebGL build names.
### **Persistence**
There's a known bug preventing the removal of session-based objects from the scene after the Client disconnects. We're working on it.
### Level of Detail
LOD levels are not properly updated when queries move or resize.
### KeyNotFoundException
When upgrading older projects to 0.9, you may get the following error after trying to connect to a Room/World:\
`System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.`\
\
If this happens, you should manually select your CoherenceSync Prefabs in the Inspector to trigger an OnGUI call.\
\
If you have any problems after trying this, please let us know on our [Discord](https://coherence.io/discord) so we can help you out.
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