Unable to open project - Creative Cloud Express

I also have this issue. I've duplicated the project. I've cleared my cache and browsing history. I've downloaded a new browser and still the same error message. I am unable to open my Project.

"Message: Error opening document version 27000;Errors: TheoDocument.children does not match schema rule: Vali..."

I started using Adobe Spark...now Express mainly for social media posts or quick posters/accessiblity from my phone. Some great features, simple and comprehesive layout program. I've been using Adobe Creative Suite for 16-ish years. My preference is InDesign typically... I do love a lot of the features on Express like photos and design assets are very handy -- why aren't they available through InDesign?? At the same time it is very buggy. Slow at times, stalls, reloads... then THIS. I'm in the middle of billing a client and making one last change to a file and now I can't open it. Several hours of my time wasted... a poster that now needs to be remade...  perhaps I can quickly edit the PDF but that's pretty unprofessional in my opinion. Gone are the days of just paying for a program and using it. Now are the times where things are automatically updated and imposed on the consumer... needing to relearn things against our will and buggy bug bugs.

I have this exact issue. My project is a grad school assignment that is due this week, so that's fun. I'm glad it's not just me?

What a complete and utter SNAFU Creative Cloud Express is.  Bug ridden, changing without warning failing to implement suitable links not providing for transitions, no effective T&Cs clarification … I can go on but please sort it out quickly so that work on a Spark project can resume.