Most of the issues you may find when running Geronimo will be at start up time; and most likely driven by some conflicting resources from the environment where Geronimo is set up.

JVM

Apache Geronimo v2.1 is Java EE 5 certified. With that said, it will likely run on different JVM versions however the results may be unpredictable. Whenever possible use jdk 1.5.

Port conflict

The second most common startup issue is associated to port conflicts, check no other application is using or blocking Geronimo's default ports:

If you identify port conflicts you can use the <geronimo_home>/var/config/config-substitutions.properties to change any of these ports. From this configuration file you can also set a port offset and have all these increased by that amount.

Keep also in mind that personal firewalls, anti virus and spyware protection products may block some of these ports as well, even if you turn off such software sometimes those "rules" are still in effect.

Refer to the Installation and configuration section for additional details on prerequisites and different configurations.