Unity 2020.3.12f1打开或创建项目时出现项目错误及找不到Package Manager本地服务器应用的问题咨询

Hey there, I’ve run into this exact Package Manager error before in older Unity LTS versions—total roadblock when trying to work on projects. Let’s walk through the most reliable fixes to get you back up and running:

Step 1: Quick Restart (Don’t Skip This!) #

• Close Unity Hub and all Unity editor instances completely
• Reboot your computer
• Sometimes the local Package Manager server gets stuck in a crashed process, and a full restart clears that up instantly

Step 2: Repair Your Unity Installation via Hub #

This is the most common fix for missing Package Manager components:

• Open Unity Hub, go to the Installs tab
• Find your 2020.3.12f1 installation, click the three-dot menu next to it
• Select Repair and let Unity Hub re-download any corrupted or missing files (including the local server app)
• Once done, try opening or creating a project again

Step 3: Clear Package Manager Cache #

Corrupted cache files often cause this error:

• Close Unity and Unity Hub
• Navigate to the cache folder based on your OS:
  • Windows: %USERPROFILE%\.cache\Unity\PackageManager
  • Mac: ~/Library/Caches/Unity/PackageManager
• Delete all files and folders inside this directory
• Reopen Unity Hub and launch your project

Step 4: Check Permissions #

Unity might not have access to the necessary files to run the local server:

• Windows: Right-click the Unity executable (or Unity Hub) and select Run as administrator
• Mac: Go to System Preferences > Security & Privacy > Privacy > Full Disk Access, add Unity and Unity Hub to the list
• Try opening your project again with elevated permissions

Step 5: Reset Package Manager Preferences #

If your Package Manager settings got messed up:

• Open Unity (if you can get to the editor—if not, skip to Step 6)
• Go to Edit > Preferences > Package Manager
• Click the Reset to Defaults button at the bottom
• Restart Unity and check if the error is gone

Step 6: Reinstall Unity (Last Resort) #

If none of the above work, a clean reinstall usually fixes deep-seated issues:

• Uninstall Unity 2020.3.12f1 via Unity Hub
• Delete any leftover files in the installation directory (default: C:\Program Files\Unity\Hub\Editor\2020.3.12f1 on Windows, /Applications/Unity/Hub/Editor/2020.3.12f1 on Mac)
• Reinstall the version via Unity Hub, making sure to select all necessary components during setup

Once you fix the Package Manager error, the additional project errors you’re seeing should also resolve themselves—most of those are caused by the Package Manager failing to load required dependencies for your project.

内容的提问来源于stack exchange，提问作者Bronze