Cannot find command `dotnet ef` out of sudden.

Issue similar to dotnet/efcore#15448 and dotnet/efcore#19861.

We’ve got a CI agent which runs the dotnet ef command in one of the steps. Out of sudden it stopped working and I receieved the same

Could not execute because the specified command or file was not found.
Possible reasons for this include:
  * You misspelled a built-in dotnet command.
  * You intended to execute a .NET Core program, but dotnet-xyz does not exist.
  * You intended to run a global tool, but a dotnet-prefixed executable with this name could not be found on the PATH

error like the others. It’s hard to tell what caused that, taking into account that it’s just a ci agent and the same routine happens there every day. I may suspect only windows update…

Nevertheless, the tool was obviously where it was before %USERPROFILE%\.dotnet\tools. I tried to reinstall it, upgrade it (from 3.0.0 to the latest 3.1.6) and restarting the pc, but nothing happened.

The path variable was correctly set, but it was a user-defined variable, not the machine one, which I believe is correct. After some struggling I simply added this user-scoped path to the machine-wide path and it started to work. Maybe this can help to investigate the issue.

[dmslowmo]

What solved it for me on Mac: Add to PATH: ~/.dotnet/tools

[KujinKrush]

I found the issue! check your global.json file and change the version. It finally works!