Did you get more than one copy of the first signed file from the other party?
If not then you should probably ask for another just in case your signed file has been corrupted along the way.
No it isn't corrupted.I'm able to decode it properly.
Check that it's definitely the right wallet you're trying to sign the transaction in also.
That could be the problem. First party have signed it using Bitcoin Core which I believe is not compatible with Electrum since it's a HD wallet.
first make sure you have installed the latest version of Electrum which currently is 3.1.3 (
https://electrum.org/#download). it is a common problem that people try to sign a transaction made by a new version, in an old version and the old version fails to understand (parse) the transaction. that is why the dialog closes.
Updated the version and now it throws an error. Unhandled expression, please report the issue.List-Index out of bound exception.
to make sure your transaction is fine you can a use an online decoding tool to verify it. like this one:
https://btc.com/tools/tx/decode if something is wrong with it then you will see an error saying "Decode failed"
Nope the JSON is valid.