javascript fails with var is undefined

Try using the CLIENT_ACCEPTED event that I used earlier to limit the addition of a record to the first connection.

Also because you aren't setting $uid in the HTTP_RESPONSE event, I don't think anything's getting added, and you're seeing the log from the HTTP_REQUEST event.

I don't think order matters, but it might make it easier to see the logic if you move the response event before the request event, since it's on the first response that you want to set the persist record.

when CLIENT_ACCEPTED {
  set add_persist 1
when HTTP_RESPONSE {
   set uid [findstr [HTTP::uri] "uid=" 5 "&"]
   if { $uid != "" and $add_persist} {
   log local0. "Adding persist value to table: $uid"
   persist add uie $uid
   set add_persist 0
}
when HTTP_REQUEST {
   set fulluri [HTTP::uri]
   set uid [findstr [HTTP::uri] "uid=" 5 "&"]
   if { $uid != "" } {
   log local0. "Using persist value uid: $uid | $fulluri"
   persist uie $uid
  } else {
     log local0. "No uid found in HTTP REQUEST | $fulluri"
  }
}

This still may not help with the fact that you said you have different clients using the same uid however.

Denny