The error message in the stack trace basically says that Studio is unable to unpack the PPTX, XLSX or DOCX file and access its content. If you open the file in Microsoft PowerPoint, Excel or Word, you will find that you are not able to open it. If the file is password-protected, you will be presented with a message asking you to enter a password, for example:

If the file can only be accessed by users with certain permissions, these 2 alerts will appear:


The file is protected and not accessible. If you unzip it with 7zip (all PPTX, DOCX, and XLSX files are small archives) you will find an unusual content and a file called
EncryptedPackage:

Some files cannot even be extracted/unzipped. When trying to do so, you will see the error. These files might have been protected with Microsoft's
Azure Rights Management: