When we uploaded multiple avatars in a row relatively quickly, we encountered an issue where the upload process would freeze without any error message shown on the console or in the log files. This issue comes from two main causes: Firstly, the VRChat SDK silently ignores exceptions that occur in VRC_SdkBuilder.RunExportAvatarBlueprint . The catch clauses has comment // Errors are handled by the error callback , but most of the exceptions do not initiate error callback, including this one. Secondly, the VRChat SDK does not handle the exception occurred when trying to delete the last uploaded .vrca file. Removing the last uploaded .vrca file is not a critical step in the upload process, so it should not cause upload to freeze. However, currently, if the deletion fails, the upload process will not continue, leading to a freeze. When we replaced catch clauses to catch (Exception e) { Debug.LogError(e); } , we were able to see the following error message in the console: System.IO.IOException: The process cannot access the file 'C:\Users\****\AppData\Local\Temp\****\****\637e8e6c-8eb6-4cd2-a651-241fb7aa6ed3.vrca' because it is being used by another process. at System.IO.FileSystem.DeleteFile (System.String fullPath) [0x0001a] in <27124aa0e30a41659b903b822b959bc7>:0 at System.IO.File.Delete (System.String path) [0x00014] in <27124aa0e30a41659b903b822b959bc7>:0 at VRC.SDK3.Builder.VRCAvatarBuilder.ExportCurrentAvatarResource (UnityEngine.Object avatarResource, System.Boolean testAsset, System.Boolean buildAssetBundle, System.String& avatarPrefabPath, System.Action`1[T] onProgress, System.Action`1[T] onContentProcessed) [0x003bc] in <81261fc1c1e94d15bda5671000ac0e16>:0 at VRC.SDK3.Builder.VRCAvatarBuilder.ExportAvatarBlueprint (UnityEngine.GameObject externalReference) [0x00021] in <81261fc1c1e94d15bda5671000ac0e16>:0 at VRC.SDK3A.Editor.VRCSdkControlPanelAvatarBuilder.Build (UnityEngine.GameObject target, System.Boolean testAvatar) [0x0040b] in .\Packages\com.vrchat.avatars\Editor\VRCSDK\SDK3A\VRCSdkControlPanelAvatarBuilder.cs:2600 UnityEngine.StackTraceUtility:ExtractStackTrace () UnityEngine.DebugLogHandler:LogFormat (UnityEngine.LogType,UnityEngine.Object,string,object[]) UnityEngine.Logger:Log (UnityEngine.LogType,object) UnityEngine.Debug:LogError (object) VRC.SDK3A.Editor.VRCSdkControlPanelAvatarBuilder/<Build>d__132:MoveNext () (at ./Packages/com.vrchat.avatars/Editor/VRCSDK/SDK3A/VRCSdkControlPanelAvatarBuilder.cs:2605) System.Runtime.CompilerServices.AsyncMethodBuilderCore/MoveNextRunner:InvokeMoveNext (object) System.Threading.ExecutionContext:RunInternal (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool) System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool) System.Runtime.CompilerServices.AsyncMethodBuilderCore/MoveNextRunner:Run () System.Threading.Tasks.SynchronizationContextAwaitTaskContinuation/<>c:<.cctor>b__7_0 (object) UnityEngine.UnitySynchronizationContext/WorkRequest:Invoke () UnityEngine.UnitySynchronizationContext:Exec () UnityEngine.UnitySynchronizationContext:ExecuteTasks () When we disabled the real-time protection of the antivirus software for the temporary folder, the upload process worked as expected without freezing. Therefore, we conclude that the issue is related to antivirus software holding a handle on the last uploaded .vrca file, which prevents it from being deleted.