.ASPX Files Now Download Instead of Launching from SharePoint

Hello all,

My organization has recently discovered an issue with .aspx files hosted on SharePoint. We've been using them to launch Storyline and Rise files so they act like web pages (like this). However, we just recently found that after reuploading the file or folder to SharePoint, SharePoint no longer opens the page. If you navigate to the .aspx file, it force-downloads the file. If you use the direct URL, you get a File Not Found error.

We suspect this is a SharePoint issue that has to do with the upload process. My IT department has asked me to check here to see if anyone else has experienced this problem, and if so, what the root cause was (e.g., Microsoft update, policy change, etc.)? 

We're looking at SharePoint because:

• It happens to multiple people in multiple offices (not a computer issue).
• It happens with Chrome and Edge. Modifying the URL to add ?web=1 has no effect. Clearing cache and cookies has no effect (not a browser issue).
• I tested the "old" file to confirm it worked, then downloaded the .zip package from SP. When I reuploaded the exact same package back to SP, the file now force-downloads/is not found (so it's not the files or the Storyline version).
• I copied a file that's still working and uploaded the copy. The original opens as a web page, the copy doesn't (again, not the files). 

Thanks in advance for your feedback!

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