My Spirent Testcenter getting this error when create stream on 10G port, this is because script set the port to 1G, then create stream with 3G load.
stc::get port1 -ActivePhy stc::delete ethernet10gigfiber1 stc::create EthernetFiber -under port1 #here script create a ethernetfiber phy under port1 which defaut to be 1G stc::apply
stc::config streamblock1 -LoadUnit KILOBITS_PER_SECOND -Load 3000000 #here stream load is 3G
So if met similar error, check if script set the phy wrongly.