Well I solved it by adding concurrent-request-timeout
<core:manager conversation-timeout="10000" concurrent-request-timeout="5000"/>
in my components.xml as I am using seam support.
I'm using the richfaces FileUpload component too. The first upload works fine, but on subsequent uploads I get the ConcurrentRequestTimeoutException. I've tried increasing the concurrent request timeout but that doesn't work for me.
Can anybody shed some light on this please?
Please try to use a4j:queue.