Don’t use ElectrumSV’s broken accumulator multi-signature

Roger Taylor
2 min readNov 8, 2020


A user has reported losing a lot of BSV because they changed the script type of their multi-signature wallet to “accumulator multi-signature”. Please stick with the default script types for all of your wallets unless you are willing to accept the risk.

There are a lot of ways to lose coins with ElectrumSV, it is an open source wallet and some call it the “swiss army knife” of wallets. Unfortunately, this means it is very possible to cut yourself.

Why does ElectrumSV have this?

Originally when we were preparing for the Genesis upgrade and the deprecation of P2SH payments, we needed to support other types of multi-signature. The code base underwent a large refactoring and part of this was preparing for the future by recording what keys were used with what script types. In order to test this we needed different kinds of scripts.

Accumulator multi-signature is the future of scripting, it is superior to bare multi-signature if implemented correctly. The idea was to replace bare multi-signature with it. However, I had no confidence I had the resources to sufficiently test it, so this is why bare multi-signature is the script type we give users for multi-signature wallets. Bare multi-signature is known, well used, well tested and safe.

What is the problem?

One of the opcodes in ElectrumSV’s implementation of accumulator multi-signature is wrong.

What now?

It is not expected that users will change the script type their account uses, unless they know what they are doing or are willing to take the risk of doing so. Unless you read the ElectrumSV code and verify for yourself some advanced setting works, or know that others are using it commonly, you should avoid changing it.

We will make a new release removing the ability to change the script type used by an account.