On Windows, after upgrading to Application Server 9.1, the samples and JES5 portal samples compete on Derby port 1527. Specifically, Application Server 9.1 automatically starts JavaDB on port 0.0.0.0:1527 with APP:APP, however the JES5 Portal JavaDB wants to bind to hostnameIP:1527 with portal:portal.
This bug describes an issue that was already seen for JES 5, Bug 6472173. The workaround for bug 6472173 is documented in the Sun Java Enterprise System 5 Installation Guide for Microsoft Windows.
Start the Derby database using the following command:
<JES installation dir>\appserver\bin\asadmin start-database --dbhome <JES installation dir>\portal\data\derby