Suddenly for some unknown reasons I started seeing this error while accessing a particular project using SourceJammer(SJ) client (ver 2.1.0.0).
Googling around I found this post by the creator of SJ where he says that in order to remove this error, we need to increase the timeout value in serverconfig.xml from default 1000 to 4000 and restart SJ (which means restart the TomCat service).
http://www.mail-archive.com/sourcejammer-users@lists.sourceforge.net/msg00473.html
This worked for me, hope this post helps others too!