pnpm is not recognized
Run Get-Command pnpm, check Corepack, open a fresh terminal, and identify whether another pnpm executable shadows the intended one.
EPERM / access denied
Check whether the project/tool is writing under a protected directory or another process is holding the file. Do not default to Administrator mode as the permanent fix.
Port 3000/4000 already in use
Find the PID owning the listening port, identify the process, then stop only the service you actually mean to stop.
Node version is wrong
Use Get-Command node and your version manager's current selection. PATH order can point to an older standalone installation.
Build differs from dev
Read the production build error first. Server/client boundaries, type errors, static generation, and environment values often surface only during build.