"Debugging and troubleshooting", "List of MyChat Client errors", "Error #0279".
Error #0279: Access denied
The attempt to access any of MyChat WEB services failed due to service denial.
Check the log on Admin Panel ("Tools", "Logs", "Logs type" — "NodeJS logs"), or, if this is impossible, check the file "C:\ProgramData\MyChat Server\logs\yyyy\mm\dd\node.log" on a computer with MyChat Server.
The log contains the information regarding the address from which the connection performs and why the WEB server denies the service.
The most frequent reason is incorrectly configured IP filters on the server.