Why do I get error code E500 when installing gulp-concat and gulp-uglifyjs?

Question

Node.js

Windows 10 system.
I write the command "npm install gulp-concat gulp-uglifyjs --save-dev" in CMD in the project directory
After a long download, an error pops up:
npm ERR! code E500
npm ERR! 500 Internal Server Error: [email protected]
Gulp, Sass, Git, Bower are installed and working, but when trying to install gulp-concat or gulp-uglifyjs, as I think any other plugins, an error pops up. I searched on the Internet, but I could not find anything about this, I ask for help, maybe someone came across, thanks in advance!

Answer 1

Found the answer at random - an error in the command, you need to write it wrong:
npm install gulp-concat gulp-uglifyjs --save-dev
And like this:
Maybe npm i concat uglifyjs --save-dev but i haven't tried it.