TAB key for Auto-complete not working in Command Prompt

If the TAB key to Auto-complete is not working in Command Prompt on Windows 10, then you need to make changes in the Registry to fix the issue. You will need to make two changes: Let’s take a look at the description of the process involved concerning each of the listed solutions.

1] Modify CompletionChar and PathCompletionChar registry values

Since this is a registry operation, it is recommended that you back up the registry or create a system restore point as necessary precautionary measures. Once done, you can proceed as follows:

Press Windows key + R to invoke the Run dialog.In the Run dialog box, type regedit and hit Enter to open Registry Editor.Navigate or jump to the registry key path below:

On the right pane, double-click on the CompletionChar entry to edit its Properties.In the properties window, set the Value data to 9.Click OK to save changes.

Next, on the right pane still, double-click on the PathCompletionChar entry to edit its properties.

In the Properties window, set the Value data to 9.Click OK to save changes.Exit Registry Editor and reboot your device.

On boot, open CMD prompt and check if the TAB key is now working normally.

2] Enable QuickEdit Mode

Next, do the following:

Press Windows key + R to invoke the Run dialog.In the Run dialog box, type cmd and then press CTRL + SHIFT + ENTER to open Command Prompt in elevated mode.In the Command Prompt window, right-click on the Command Prompt title bar.Now, click on Properties.In the Edit Options section, check the option QuickEdit Mode.Click on OK to save changes.

The TAB key should start working as expected and the issue should be now resolved. Hope this helps!