The log files, server.log or catalina.log contain log messages of type: No buffer space available (maximumconnections reached?): connect.
This can lead to unexpected failures, like failing to login or Database errors when nothing is wrong with the Database.
This issue is related to a bug in Windows Server 2008 R2.
Users logging into WebCenter must try 4-5 times before being granted access.
Besides the multiple tries necessary to login, an inspection of the JBOSS log file shows following errors:
at org.jboss.resource.connectionmanager.PoolFiller.run(PoolFiller.java:75) [:6.1.0.Final]
at java.lang.Thread.run(Thread.java:662) [:1.6.0_41]
Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: The TCP/IP connection to the host DS089014, port 62241 has failed.
Error: "No buffer space available (maximum connections reached?): connect. Verify the connection properties.
Make sure that an instance of SQL Server is running on the host and accepting TCP/IP connections at the port.
Make sure that TCP connections to the port are not blocked by a firewall."
This issue is caused by a bug in Windows Server 2008 R2.