ProxyPass intermittent errors

I can't see how the bypass variable couldn't be read given just that rule. The variable is being set on every HTTP request and isn't being unset anywhere. Do you have another rule on the same VIP which uses a variable named $bypass and unsets it (grasping at straws...)?

You could add a check to see if the variable isn't set. It wouldn't solve the problem but could allow you to handle the error and possibly log some debug info.

   
  if {[info exists bypass]}{   
     if {1 != $bypass} {   
  ...   
  } else {   
      Log some debug here on the connection details to try to figure out why $bypass isn't set?   
  }   
  

Aaron