[BUG] mcpServers in claude_desktop_config.json silently ignored on Windows MSIX install (v1.1.8629.0)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Environment:

App version: 1.1.8629.0 (MSIX/Windows Store install)
OS: Windows
Install path: C:\Users\<user>\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\
Plan: Pro

What's wrong:
MCP servers configured in claude_desktop_config.json are never started. They do not appear in Settings → Developer, and no mcp-server-*.log files are ever created. Claude loads its own built-in servers (Chrome extension, office-addin, mcp-registry) successfully but completely ignores user-defined mcpServers entries.
Steps to reproduce:

Install Claude desktop via https://claude.com/download (Windows MSIX installer)
Add mcpServers block to claude_desktop_config.json at both:

%LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\claude_desktop_config.json
%APPDATA%\Claude\claude_desktop_config.json

Fully quit and restart Claude
Navigate to Settings → Developer — "No servers added" is shown

Config used:
json{
"preferences": {
"coworkScheduledTasksEnabled": true,
"ccdScheduledTasksEnabled": true,
"sidebarMode": "chat",
"coworkWebSearchEnabled": true
},
"mcpServers": {
"google-calendar": {
"command": "C:\\Program Files\\Docker\\Docker\\resources\\bin\\docker.exe",
"args": ["run", "--rm", "-i", "-v", "google-calendar-mcp-tokens:/tokens",
"--env-file", "R:/mcp/google-calendar/.env", "google-calendar-mcp:latest", "serve"]
}
}
}

(Additional servers omitted for brevity — same pattern)

**Relevant log entry** from `%LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\logs\main.log`:

2026-03-25 09:07:49 [error] Error reading or parsing config file: {
error: SyntaxError: Expected ',' or '}' after property value in JSON at position 168 (line 8 column 3)
Both config files validate successfully with ConvertFrom-Json in PowerShell — the source of this parse error is unidentified.
Additional findings:

No mcp-server-*.log files are ever created, indicating servers are never attempted
The "Edit Config" button opens %APPDATA%\Claude\claude_desktop_config.json — this is the known two-file MSIX bug documented in issue #26073
Both files have been kept in sync and both contain valid JSON with mcpServers
Docker is installed at C:\Program Files\Docker\Docker\resources\bin\docker.exe and works correctly from terminal
Node.js v24.14.0 is also available

Related issues: #26073

What Should Happen?

mcp servers should load, or logs should be created indicating the issues with servers not loading

Error Messages/Logs

Steps to Reproduce

Environment:

App version: 1.1.8629.0 (MSIX/Windows Store install)
OS: Windows
Install path: C:\Users\<user>\AppData\Local\Packages\Claude_pzs8sxrjxfjjc\
Plan: Pro

What's wrong:
MCP servers configured in claude_desktop_config.json are never started. They do not appear in Settings → Developer, and no mcp-server-*.log files are ever created. Claude loads its own built-in servers (Chrome extension, office-addin, mcp-registry) successfully but completely ignores user-defined mcpServers entries.
Steps to reproduce:

Install Claude desktop via https://claude.com/download (Windows MSIX installer)
Add mcpServers block to claude_desktop_config.json at both:

%LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\claude_desktop_config.json
%APPDATA%\Claude\claude_desktop_config.json

Fully quit and restart Claude
Navigate to Settings → Developer — "No servers added" is shown

Config used:
json{
"preferences": {
"coworkScheduledTasksEnabled": true,
"ccdScheduledTasksEnabled": true,
"sidebarMode": "chat",
"coworkWebSearchEnabled": true
},
"mcpServers": {
"google-calendar": {
"command": "C:\\Program Files\\Docker\\Docker\\resources\\bin\\docker.exe",
"args": ["run", "--rm", "-i", "-v", "google-calendar-mcp-tokens:/tokens",
"--env-file", "R:/mcp/google-calendar/.env", "google-calendar-mcp:latest", "serve"]
}
}
}

(Additional servers omitted for brevity — same pattern)

**Relevant log entry** from `%LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\logs\main.log`:

2026-03-25 09:07:49 [error] Error reading or parsing config file: {
error: SyntaxError: Expected ',' or '}' after property value in JSON at position 168 (line 8 column 3)
Both config files validate successfully with ConvertFrom-Json in PowerShell — the source of this parse error is unidentified.
Additional findings:

No mcp-server-*.log files are ever created, indicating servers are never attempted
The "Edit Config" button opens %APPDATA%\Claude\claude_desktop_config.json — this is the known two-file MSIX bug documented in issue #26073
Both files have been kept in sync and both contain valid JSON with mcpServers
Docker is installed at C:\Program Files\Docker\Docker\resources\bin\docker.exe and works correctly from terminal
Node.js v24.14.0 is also available

Related issues: #26073

File it at: https://github.com/anthropics/claude-code/issues/new

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.78 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_