To use the tomcat manager app in an Alfresco installation you have to modify some settings:
A admin-user has to created in the …/tomcat/conf/tomcat-users.xml
...
<tomcat-users>
...
<user username="admin-usa" roles="manager-gui,manager-script,manager-jmx,manager-status,admin-gui,tomcat" password="admin-password" />
..
</tomcat-users>
Aditionally the SSL Authenitcator has to be disabled:
In the file …/tomcat/conf/context.xml comment out the line
<Valve className="org.apache.catalina.authenticator.SSLAuthenticator" securePagesWithPragma="false" />
.. and restart Tomcat.