Looks like Odin runs a step to force update the GUIDs of its DLLs, but it doesn't use Unity's version control to do so, so in Perforce it will fail if it needs to make a change.
A related issue is that I only discovered this because Unity re-serialised a bunch of files, which made Odin's DLLs' GUIDs become lower-case (the canonical form of GUIDs in Unity), and it looks like Odin by default wants to make GUIDs upper case.
I suggest Odin should write out lower case GUIDs, and should use Unity's version control API to check out files before writing to them. Thanks
1. What happened?
This error message:
Could not update asset guid for assembly Sirenix.Serialization.Config.dll. Access to the path "E:\projects\BenHymers_Davy_Gorge_1\TPC\Assets\Plugins\Sirenix\Assemblies\Sirenix.Serialization.Config.dll.meta" is denied. UnityEngine.Debug:LogError(Object) Sirenix.Utilities.Editor.PersistentAssemblyGuidUpdater:LogError(Assembly, String) (at X:/Repositories/sirenix-development/Sirenix Solution/Sirenix.Utilities.Editor/AssemblyUtils/PersistentAssemblyGuidUpdater.cs:123) Sirenix.Utilities.Editor.PersistentAssemblyGuidUpdater:UpdateGuids(Boolean) (at X:/Repositories/sirenix-development/Sirenix Solution/Sirenix.Utilities.Editor/AssemblyUtils/PersistentAssemblyGuidUpdater.cs:99) Sirenix.Utilities.Editor.<>c:<Init>b__0_0() (at X:/Repositories/sirenix-development/Sirenix Solution/Sirenix.Utilities.Editor/AssemblyUtils/PersistentAssemblyGuidUpdater.cs:21) UnityEditor.EditorApplication:Internal_CallDelayFunctions()
2. How can we reproduce it?
Make an ODIN DLL meta file GUID contain some lowercase characters, and version it in Perforce. To check that the error happens though, it’s enough to make the file readonly - this is what Perforce does until manually checked out.
3. If screenshots would help explain or demonstrate your issue, please include these.
4. What version of Unity are you using?
5. What version of Odin are you using? (See "Tools > Odin Inspector > About")
6. Do you have Editor Only mode enabled?
7. What operating system are you on?
Windows 10 Pro 1909