Failed to execute script electrum

I have some litecoins on electrum wallet ltc on version 2.9.3 . The wallet has been downloaded from When trying to open my wallet from electrum v3 error “failed to execute script electrum” is shown.
Is there incompatibility?
Is there any way to overcome that? Should I just stay on wallet ltc on version 2.9.3?
Another question, is there any difference on wallets provided from site ?
My platform is windows 7.

Thanks a lot