Amazon Q Language Client fails with "The JSON-RPC connection with the remote party was lost before the request could complete"

**Describe the bug**
When trying to use Amazon Q in Visual Studio 2022, I get this error:

Failed to initialize Language Server: Amazon Q Language Client
- Status: SendingInitializeRequest
- Status Message: Sending 'initialize' request
- Exception: The JSON-RPC connection with the remote party was lost before the request could complete.

The error appears when starting up Visual Studio. It re-appears after using the 'Sign in' function in the 'Getting Started' window. Because of this, it is not possible to start an Amazon Q chat in Visual Studio.

**To Reproduce**
1. Start Visual Studio
2. Open a solution with C# code.
3. Open output window
4. Choose 'Show output from: Amazon Web Services'
5. The error message appears
6. Open menu Extensions / AWS Toolkit / Getting Started
7. Click on Sign out and then Sign in again
8. The same error appears in the Output window
9. Open menu View / Amazon Q Chat
10. Message "Looks like there isn't any code open in your workspace" appears. There is no chat prompt.

**Expected behavior**
Amazon Q chat works, like in my other IDE JetBrains Rider.

**Toolkit Logs**
[log_2025-09-18_16-32-23_24460.txt](https://github.com/user-attachments/files/22408843/log_2025-09-18_16-32-23_24460.txt)

**Development System (please complete the following information):**
- Windows Version: Windows 11 version 24H2 (OS Build 26100.4946)
- Visual Studio Version: VS Professional 2022 17.14.15
- AWS Toolkit for Visual Studio Version: 1.78.0.0

**Additional context**
- Apart from Amazon Q, the other functions of AWS Toolkit work. For example: I can browse through AWS resources.
- I also have JetBrains Rider on my computer. The Amazon Q plugin works without issues in Rider.
- My co-workers don't have this issue.
- I already tried uninstalling AWS Toolkit and Visual Studio, and deleting directory "C:\Users\{username}\AppData\Local\AWSToolkit", but keep getting the same error.
- I already tried importing VS settings from a co-worker, but keep getting the same error.

Start with the attached Toolkit log and the Amazon Web Services output in Visual Studio, following the listed startup and sign-in reproduction steps. Compare the failing Amazon Q Language Client initialization with the working Rider setup and verify the Amazon Q Chat view. Done means the JSON-RPC connection initializes successfully and the chat prompt is available for an open C# solution.

Written by the indexing model from the issue text.