Description:

I have upgraded v3.0.7 to v3.6.0, and after upgrade PDF document preview is not working anymore, instead I see following errors in browser console:

Uncaught (in promise) Error: Removed API method: PDFDocumentLoadingTask.then, use the `promise` getter instead.
    at r.then (/node_modules/pdfjs-dist/build/pdf.js:23)

Steps to reproduce:

• Try to preview any uploaded PDF file in chat by clicking on the right arrow

Expected behavior:

• document preview is shown

Actual behavior:

• document is not shown and spinner spins forever
• above mentioned error is shown in browser console

Server Setup Information:

• Version of Rocket.Chat Server: 3.6.0
• Operating System: CentOS 7.7
• Deployment Method: tar
• Number of Running Instances: 1
• NodeJS Version: v12.14.0
• MongoDB Version: 4.0.20

Client Setup Information

• Desktop App or Browser Version: Chrome 85.0.4183.83 (Official Build) (64-bit) & Firefox 80.0.1 (64-bit)
• Operating System: Windows 10 Pro

Additional context

• Server is upgraded from version 3.0.7 . Server is working without issues for more than 2 years now. All data is preserved and everything else seems to be working fine.
• PDF file download works fine, just preview is affected

Relevant logs:

• No relevant logs on server