I'm just trying out MyHeritage to see how it works. I added some of my information and exported it as a GEDCOM to make sure I could get my data out. Then when trying to import that GEDCOM file to another site to test it (ancestry.com), it says the GEDCOM is not valid.
I have some info in ancestry.com but they don't appear to allow you to export to GEDCOM (a requirement for me), but if the GEDCOM exported from MyHeritage is not valid, I have essentially the same issue.
The Gedcoms that are exported from both MyHeritage.com and Family Tree Builder are standard Gedcom files that should be accepted on sites such as Ancestry.com.
Have you contacted their support to ask them if they accept standard Gedcoms from other sites?
I am also having the same problem. I maintain my tree on myHeritage & export it ancestry to search for records. It has always worked in the past but suddenly has stopped working since upgrade. I will ask ancestry for help to.
Error: The file you have specified (Newest gedcom try2.GED) does not appear to be a valid GEDCOM file, please try again.
We just had another user that had the same problem, and they informed us that Ancestry had a problem with their site that prevented the Gedcom from being imported.
Please contact their support to find out if the issue has been resolved yet.