Unreal Engine - Most modules from engine are excluded. UBT logs "Unable to instantiate module 'DiaSdk'"

Problem

When Unreal Engine (UE) is used with Rider and the Engine/UE project is set as the startup project, not all plugins and projects are indexed as expected. Some engine modules and plugins that are part of the configuration are incorrectly marked as excluded. Code highlighting is missing in related files or shown as non-resolved

Cause [Optional]

The issue might be related to an incorrect DIA SDK path. The Unreal Editor project cannot generate the necessary JSON file (UnrealEditor.json) due to a failure in locating the DIA SDK directory. This results in an exception during module instantiation (DiaSdk). The specific error mentions:

Unable to find DIA SDK directory

The DIA SDK directory was not correctly aligned in the system paths, which prevented proper processing and inclusion of the engine modules for indexing.

Resolution

To ensure that is the issue, check the UBT_GPF.txt log in Rider logs directory (Help | Diagnostic | Show Logs in {OS File Manager}. Search for exceptions like: with exact message Unable to find DIA SDK directory;

Exception while generating include data for Target:UnrealEditor, Platform: Win64, Configuration: Development
Unable to instantiate module 'DiaSdk': System.Exception: Unable to find DIA SDK directory
   at DiaSdk..ctor(ReadOnlyTargetRules Target) in D:\{pathToEngine}\Engine\Source\ThirdParty\DiaSdk\DiaSdk.Build.cs:line 15
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
   at System.Reflection.MethodBaseInvoker.InvokeConstructorWithoutAlloc(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)

If there is a similar exception, ensure that the DIA SDK path is correctly configured in the AutoSDK directory (in case the toolchain is portable) or any Visual Studio directory. Verify that the DIA SDK exists under the expected path (e.g., D:\AutoSDK or C:\Program Files\Microsoft Visual Studio\2022). In typical scenarios the path is C:\Program Files\Microsoft Visual Studio\[Year]\[Edition]\DIA SDK . In usually installs together with MSVC toolchain (Desktop Development with C++).

After ensuring the "DIA SDK" path exists, re-open the project in Rider. If that doesn't help, contact Rider support (Help | Contact Support) or look for another solution using the suspicious exceptions/errors from the UBT_GPF.txt log.