session_start(): The session id is too long or contains illegal characters

I am using MAC OSX Yosemite 10.10.3.

We installed MAMP and successfully launched SQL Server Apache and MAMP's top screen.

However, if you open the tool →phpMyAdmin from here, the following error occurs and SQL editing is not possible.

I checked with the error code, but there was only information about permission confirmation.
(Permission for /Application/MAMP/tmp/php.)

Is there an incorrect character in the ID of the session?
Where can I start?