1This is not a definitive answer but it looks like your global packages are corrupted in some way.
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3This bug may be caused by many different things. I suggest doing the following.
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51 Install Node Version Manager (or NVM for Windows) and install Node version 10.16.1. This is enough for angular 9 and from my experience it is the most stable version for development. This should also change your NPM version so that may also help.
62 Uninstall global angular package npm uninstall -g @angular/cli
73 Force clear cache npm cache clean --force
84 Just to double check npm cache verify
95 You can also try clearing your %temp% and %roaming% AppData/npm-cache
106 install latest angular package npm install -g @angular/cli@<your-version>
117 if this error still occurs, consider using another shell
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13If this don't solve the problem try to manually locate the package.json file that is throwing an error and investigate.
1Open Windows Powershell as admin
2npm cache clean --force
3solved the problem for me
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5Alternative : You can use yarn instead
6npm install -g yarn