Same here.
Error 7 with twrp 3.5.2.0, 3.5.1.0 and previous twrp versions.
It only works with the chinese twrp "3.4.2b-1206-K30Pro-wzsx150".
I tried a full reset off the phone (factory reset, delete/format all except system-partition) but the recommend twrp doesnt work.
Any ideas/solutions...