Hi SureshFep,
if you are looking for that exact string, and there are no variations in it,
the easiest regular expression in the world is
"/GET \/FIM\/sps\/acde\/saml20\/logininitial\?RequestBinding=HTTPPost\&ResponseBinding\=HTTPPost\&Target=https:\/\/cuserv\.acblue\.org\:443\/cussvc\/home\.do&NameIdFormat\=email HTTP\/1\.1\"\s*500/"
(ommit the leading and trailing quotes)
you simply specify the full string and escape each and every character known to Regular Expressions as a special character, for example
slash ("/") and dots ("."), I simply added a escape character for each and every special character.
At the end you'll see
"HTTP\/1\.1\"\s*500/"
which means that there can be as many spaces as you like between the >HTTP/1.1"< and the >500<
Greetings
Siggi