Updated to the latest version of muse and when opening 2017 file with 2018 software, receive this error. Cannot open file. Crashes every time with same error.
If possible open your file in muse 2017, delete all 3rd party widgets and certain video widgets, save as new file.
Open a copy of that file in the muse 2018.
Many appologies to find you in this trouble.
However, would you mind sharing your .muse file with us so that we can investigate and try fixing it.
For sharing the file you can upload it to Dropbox or WeTransfer and send the link to me in a private message.
For doing a private message hover the mouse on my picture and click "message".