Cannot find command 'dotnet ef'?

For those who encountered the issue after updating their Visual Studio or .NET Core package this is due to updates made in .NET Core 3 by removing dotnet ef from .NET Core and making it a separate package which can be installed via:

dotnet tool install -g dotnet-ef

For reference see this answer and this breaking change

In my case, the tools folder didn't exist inside %USERPROFILE%\.dotnet\ so I had to run the command dotnet tool install --global dotnet-ef to install dotnet ef. Then I was able to run dotnet ef...

This was the result of the above install command:

Note to readers: If you haven't installed dotnet ef, you need to install it first: dotnet tool install --global dotnet-ef. The question-asker already did that. You need to do that first before the rest of this answer can help.

How to fix this

For Linux and macOS, add a line to your shell's configuration:

• bash/zsh:

  export PATH="$PATH:$HOME/.dotnet/tools/"
  

• csh/tcsh:

  set path = ($path $HOME/.dotnet/tools/)
  

When you start a new shell/terminal (or the next time you log in) dotnet ef should work.

For Windows:

See this question on how to add to the PATH environment variable.

You need to add %USERPROFILE%\.dotnet\tools to the PATH.

What's going on?

The .NET Core 3.0 (preview) version of this failure is much more illuminating:

$ dotnet ef
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-ef 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.

The second and the third one both refer to dotnet trying to find a dotnet-ef command but can't find it. As the third point says, dotnet-ef is not in your path.

Here's what the docs say:

Global Tools can be installed in the default directory or in a specific location. The default directories are:

OS Path

Linux/macOS $HOME/.dotnet/tools

Windows %USERPROFILE%\.dotnet\tools

So, you should add $HOME/.dotnet/tools/ to your $PATH.

But also note this part from docs:

These locations are added to the user's path when the SDK is first run, so Global Tools installed there can be called directly.

So, it sounds like something went wrong. If you installed using a manual tarball, the SDK screwed up and you should report this bug to Microsoft. If you use a distribution package, they screwed up and you should report this as a bug to them.