This coronal mass ejection (CME) should be benign. A very large one, on par with what NASA infers hit the Earth in 1859, would bathe the entire planet in a multi-megavolt/m EMP (say 5000k V/m) wave that lasts for several minutes. The Starfish Prime space burst that blew out streetlamps hundreds of miles away in Hawaii was about 5.6k V/m. Standard modern warheads produce approximately 50k V/m and it's speculated the we and the Russians have EMP bombs that produce 1000-2000k V/m, but the pulse lasts for miliseconds, not the multiple minutes of a large CME wavefront.
A 5000k V/m CME would fry every transformer and electrical component in the world. For all intents and purposes, no more transportation, communications, or agriculture. I've seen models that show that world population would crash to less than 50-100 million souls. This is not something I prepare for btw.
And people wonder why SETI doesn't hear anything. The universe is a dangerous neighborhood.