Adobe Spark: Bad connection / Error: E_FETCH_COMPOSITION / Status: 500

That's a good idea: deleting old projects. Because part of my suspicion initially was memory or bandwidth or something within my own Adobe account! 

I did learn that a primary reason I was getting the message is because the projects I was working on incorporated a corporate font that I needed to upload. The font isn't part of Adobe's own font library, and it doesn't play well with Adobe Spark for that reason. It either stalled all of my videos or in the case of graphics, would get corrupted every time I came back and reopened an existing project (the text would have suddenly changed to a different weight, spacing, etc.). My recommendation if you're using unique fonts is to either be patient or (in the case of videos) find a font substitute within Spark's native environment that looks similar.

Two things that may help:

1. enter the URL for the project in the URL bar, but before hitting enter or loading the page, add this to the end of the URL: "/repair" ... that'll scrub the video of anything that's broken, ostensibly

2. In my case, the problem was the font I was using. It's a corporate font that Adobe doesn't have in its library, so I had to upload the font as a piece of the Brand I was working with. Sometimes videos would fix if I tried the previous suggestion, and typed "/repair/gingerfonts" or something similar. Otherwise, my other suggestion if you're making a video is to find a similar font within Adobe's native libraries and use that instead.

Nothing yet.  Hope they fix it soon.  I'm about to give up on Spark presentations because of it.  Find any alternatives?