Why do I receive the error "Unable to save login information. You are currently signed in but you will be prompted to sign in again the next time that you start this application"?

When launching MATLAB, why do I receive the error "Unable to save login information. You are currently signed in but you will be prompted to sign in again the next time that you start this application"?

Answer 1

[MathWorks Support Team]

If this error occurs when attempting to start MATLAB, there may be an issue with the MathWorks Service Host.

To resolve this, please try resetting your local credentials with the following steps:

Step 1: Close all running MATLAB windows.

Step 2: After closing MATLAB, execute these exact two commands depending on your OS to kill the MathWorksServiceHost process and remove the user-specific credentials folder: 

Windows

In Windows Command Prompt, execute these two commands:

Taskkill /IM MathWorksServiceHost.exe /F 
rd /s /q %APPDATA%\MathWorks\credentials

Linux

In Linux Terminal, execute these two commands:

killall MathWorksServiceHost 
rm -rf ~/.matlab/credentials

macOS

In Mac Terminal (Finder -> Applications -> Utilities -> Terminal.app), execute these two commands:

killall MathWorksServiceHost
rm -rf ~/Library/Application\ Support/MathWorks/credentials

Step 3: Try running MATLAB again.

If this does not work, perform a clean reinstall of the MathWorks Service Host:

How do I uninstall and reinstall MathWorks Service Host?

https://www.mathworks.com/matlabcentral/answers/1815365

If this error occurs when attempting to start up

MATLAB Connector

on macOS, there may be an issue with the secrets file contained with the credentials directory, which may have been deleted or modified. 

To resolve this, perform the following:

1. Delete the following directory: /Users/$USER/Library/Application Support/MathWorks/credentials
2. Delete the "MathWorks Key" key found in your login keychain in the Keychain Access app under Utilities
3. Restart MATLAB Connector

[jkr]

The upper part of this answer worked for me. Note that I did not delete ~/Library/Application Support/MathWorks/credentials, but rather only its content, a single xml file.