The ADB command cannot be used after SDK manager is upgraded.

After SDK manager is upgraded and several earlier API packages are installed, the following error occurs when you use the "ADB" command again in cmd:

"ADB is neither an internal or external command, nor an executable command.ProgramOr batch files ."

After thinking about nothing in the directory for a long time, I found that I was looking for adb.exe under Android-SDK/tool.

Open Android-SDK/tooldiscovery without the adb.exeprogram, but there is a document name named “adb_has_moved.txt"

Open it and write it into it

"The ADB ToolHas moved to platform-Tools/
If you don't see this directory in your SDK,
Launch the SDK and AVD Manager (execute the android tool)
And install "android SDK platform-Tools"
PleaseAlso update your path environmentVariable
Include the platform-tools/directory, so you can
Execute ADB from any location.
"

Adb.exe is migrated to the platform-tools/directory. You only need to add this directory under the Environment Variable path.

Android SDK is very considerate ~