I have had this problem too, I live in New Zealand. First happened after 800kms bike shop did diagnostics and couldn’t find anything, after it happened again lots of time they finally replaced the connector wire from battery to motor. Problem solved ! Nope after another 800kms E10 E20 error again. I have cleaned all contacts & have a water proof cover I put on engine when travelling, so know it isn’t dirty contacts. Bike shop are now replacing battery saying that is the problem. Time will tell but I don’t think it will help. It is winter now so I will not be riding it much so might be a few months before I click up another 800kms. It is a Merida e big tour 700
I suggest ask the shop to apply dielectric grease directly to the gold contacts on connector . As in the image above you would apply the grease directly to the 4 gold spades stiking out from connector. In my view the issue is related to contacts rubbing more than dust/dirt getting in...grease stops contacts rubbing and wearing. Seems counterintuitive but take it from an electronic engineer fretting is a common contact Issue in automotive industry
You can get grease from repco or supercheap.
I can't guarantee it will work but I'm now at 5000ks with no issue, I commute daily on very similar bike.