is there any other issues other than lens to camera communication which can cause the err01 code to appear
as I have cleaned the contacts and it works fine for a while then plays up and locks me out. The other lens there is no problem
If it's only one lens and it re-occurs after cleaning the lens contacts then it may be an internal lens issue. Perhaps with a loose ribbon cable.
You don't mention the lens but if you do searches for err01 the 24-105 seems to be a lens where this occurs on occasion.
Canon service may be needed.