I recently reinstalled Vagrant, a way to create reproducible virtual machines, on my Windows laptop after its hard drive died. The install completed successfully, but when I opened a new command prompt (fine, Git Bash running inside Console2), it was not able to find the vagrant or vagrant.bat binary. It would work, however, when I opened a command prompt from the task manager(?!).

Some Googling revealed that changes to the PATH are not propagated to other processes until the next login/reboot. This was too invasive for me so I opted to only restart the Windows shell:

1. Open the task manager.
2. Kill all instances of Windows Explorer/explorer.exe.
3. Click File → Run, type explorer.exe into the box that appears, and press OK.

Once the taskbar reappeared, I opened Git Bash to find that Vagrant works now.