I just got one of those, too. The article previews fine from the Overlay Creator. It builds the folio successfully but craps out mid upload.

The only interactivity I have going is an MSO with buttons to activate each state. I even deleted everything else from the pasteboard. Thisvis by far thevleast complicated page I've produced. As I mentioned, it previews correctly.   I did get a messagevto update AIR, which I did, beforevI was aware that there was a whole new drop. I'm wondering if that didn't screw everything up with that update.(I keep hitting "V" instead of the spacebar.)

I was able to upload different file (that contained just text and an image-no interactivity), and it worked. There's something specific about the other file I've been trying and I can't figure out what. I agree, some Adobe input here would be appreciated.

You, sir, are a genius. I am typically strict with filevnames, but considerably less so with layers or, in this case, the name of one of he states in the MSO. Cursed ampersand! I send you a virtual beverage of your choice.

I also just spent all day struggling with this and discovered a "HUGE GOTCHA."

As Adobe has said:

Issue

When you add an article to a folio in the Folio Builder panel in InDesign CS5 or CS5.5, you receive the following error:

"The upload has failed. [svr:ConvertUnknownError]."

The error appears during the upload process.

Solution

Remove special characters from names of overlay layers, multistate objects or their state names, or other strings applied to content that contributes to the article overlays. For example, remove ampersand, forward slash, colons, and so on [&/:\#!@].

This "Special Character" issue also seems to relate to the "<" and ">" characters that InDesign automatically puts around any object (visible in the layer palette) you create in your document. And if you have nested groups of objects these layers of "<>" can get quite deep.

I had to go hunting through layers and layers of grouped objects to delete all the "<>" and then I finally got past the "svr.ConvertUnknownError."

But once I got the error on a page it seemed to corrupt the page somehow and I had to either try to delete the page (which sometimes it would not allow me to do so I was stuck with a "dead page that wouldn't upload and I couldn't delete) or re-upload as a completely new page.

This seems to be a major flaw. InDesign automatically inserts  "<>" characters that end up killing pages when they are made into Multi State Objects and thus forcing users to go back and delete all these characters that they didn't type in originally.

Also watch out for when you have a text box with type in it and you group that into an MSO. InDesign automatically likes to name that text box for you based on the actual words in that text box. So if those words contain special characters then you could also be in trouble.