My simulations worked fine and I could collect and store the results of various .measure lines. Incrementing .param a= by steps of 0.1 worked fine. Suddenly the simulation aborts when using parameter a values that had already worked before without any problems. Error message: trouble with node "_bsx_" And the node names vary... No changes were made to the circuits as I was happy I got them finally working the way I wanted. Everything was fine, but suddenly... Ooooops... Here is a public copy of my schematic: https://easyeda.com/editor#id=618c4d6d0e754bb6a9b14e180fa4ef00