Visual Studio 2017技术咨询：编辑器主题失效、登录失败及用户上下文异常

Hey there, let's work through these two frustrating VS 2017 problems you're facing—they're pretty common, and I've got actionable fixes for both:

1. Text Editor Stuck on White Background (Theme Colors Not Applying) #

If your theme's default color scheme isn't loading and the editor stays white, try these steps:

• Reset Visual Studio Settings: Open VS, go to Tools > Import and Export Settings > Reset all settings. Choose whether to save your current settings first, then reset to default. Corrupted settings files often cause theme rendering issues.
• Re-verify Theme Selection: Head to Tools > Options > Environment > General, double-check that you've selected your desired theme (Dark, Light, etc.), click OK, then restart VS to apply changes.
• Clear VS Component Cache: Close VS entirely, navigate to %LOCALAPPDATA%\Microsoft\VisualStudio\15.0_<your-instance-id>\ComponentModelCache, delete all files in this folder, then restart VS. Cached UI components can get corrupted and break theme styling.

2. "usercontext cannot be null" Error & Corrupted Account Context (Login/Update Failures) #

For the account-related errors when trying to log into extensions or access updates, these fixes should resolve the corrupted user context:

• Reset User Data via Command Line: Close VS, open Command Prompt as Administrator, and run this command:

  devenv /resetuserdata
  

  This will wipe VS's stored user account data. Restart VS afterward and re-log into your account.
• Terminate All VS Background Processes: Open Task Manager, end every process related to Visual Studio (including devenv.exe, any Visual Studio Installer processes, and VS background services). Sometimes stuck processes prevent proper account syncing.
• Repair VS Installation: Launch the Visual Studio Installer, find your VS 2017 instance, click Modify > Repair. This fixes corrupted installation files that often cause account and extension functionality to break.

Give these steps a shot—most of the time, one of them will get things back to normal. If you hit any snags with a specific step, feel free to ask for more details!

内容的提问来源于stack exchange，提问作者Tristan