Testnet Mac uses the wrong Master Public Key

[nvmind]

We are trying to setup a Testnet multi-sig wallet between windows and Mac users. The Mac provides a MPK starting with xpub it wont be excepted by Windows wallets which issue tpub MPK's. Is there a solution to this?

[pooya87]

The Mac provides a MPK starting with xpub

your Mac wallet is creating a MainNet wallet for you if the master public key starts with "xpub". the master public key prefix for TestNet is "tpub".
in your Mac you have to run the Electrum instance with --testnet command appended to it. i am not familiar with Mac, if there is a console or something run

Code:

electrum --testnet

that should do the trick.

edit: this might help: https://bitzuma.com/posts/a-beginners-guide-to-the-electrum-bitcoin-wallet/#testnet-on-mac