solution-Error: EPERM: operation not permitted, mkdir 'C:\Users\Dishani' command not found: create-next-app code example

Example 1: Error: EPERM: operation not permitted, mkdir 'C:\Users\SHUBHAM~KUNWAR' command not found: create-react-app

Open Terminal
Go to c:/users and run dir /x 
check shorter name of your usernsme you found with dir/x 
//In my case my username is Nandini Jain and I got short id= NANDIN~1
and run npm config set cache "C:/Users/<shortname-you-found-with-dir/x>/AppData/Roaming/npm-cache" --global
//I ran the command
//C:/Users/NANDIN~1/AppData/Roaming/npm-cache" --global

HOPE THIS WILL WORK BECAUSE ITS THE ONLY REASON OF YOUR QUERY.

Example 2: Error: EPERM: operation not permitted, mkdir 'C:\Users\Anubhab' command not found: create-react-app

Open terminal
to go to "C:/Users>" type: cd..
then run: dir /x
// this will show you your short id: ANUBHA~1 for username: Anubhab Mukherjee
then run: npm config set cache "C:/Users/<short-id-you-got>/AppData/Roaming/npm-cache" --global
// in my case
// npm config set cache "C:/Users/ANUBHA~1/AppData/Roaming/npm-cache" --global

then run desired npx command
THIS MIGHT SOLVE YOUR PROBLEM