@Tom UX Chang - I have not run into this and cannot find any documentation referencing limits on the number of documents a user can upload by plan type, only file size limitations (30 MB). I just tired uploading the same 512 KB PDF and did not receive any errors. 

Some questions/things to try:

• “have uploaded three pdfs but when I upload a fourth one”
  • On the board where you have uploaded three, but cannot upload this fourth one - are you able to upload one of the three successfully uploaded PDFs again?
  • Perhaps even another PDF besides the trouble one?
  • Are you able to upload it to another board in your Free Plan team?
• “The document creator was able to upload this document”
  • ​​​​​​​Was the creator of the PDF document able upload the PDF to the same board that you cannot upload it to?

​​​​​​​Are you able to upload this PDF through the same browser to any other web service, e.g., Google Drive or OneDrive?

Some related help articles:

• Uploading Files to Boards
• Support File Formats

@Rob Johnson - in response to your questions:

• On the board where you have uploaded three, but cannot upload this fourth one - are you able to upload one of the three successfully uploaded PDFs again?  Yes
• Perhaps even another PDF besides the trouble one?  
  • 101 KB - Yes
  • 466 KB - Yes
  • 68 KB - Yes
  • 78 KB - No
  • 77 KB - Yes
• Are you able to upload it to another board in your Free Plan team?  No, not even someone else’s shared board 
• “The document creator was able to upload this document”
  • Was the creator of the PDF document able upload the PDF to the same board that you cannot upload it to? Haven’t asked because she was able to insert into her board and she has a free plan.    
• Are you able to upload this PDF through the same browser to any other web service, e.g., Google Drive or OneDrive?  Yes, able to upload to Google Drive I downloaded templates from Design Thinking Practice Assignments (https://www.curiositytank.com/resources), #4 is the problem one.   
• Good news:  The Miro Support & Help Center has been able to reproduce the issue with the PDF I provided and found there was an error in the console relating to the external library they use when uploading PDFs.  They have reached out to their development team to look at solutions and possible workarounds if there are any.  Stay tuned. 

Thanks for your help.  

@Tom UX Chang Thanks for taking the time to answer all of those questions even though it appears to be a code/library-related issue. I’m glad to hear it’s being looked into 

@Rob Johnson No problem, I know what it’s like to be on a help desk so I try to be thorough before reporting bugs.  I have even recorded my screen to demo a problem for another help desk.  

Has there been any resolution to this issue?  I am having the same issue.  Three PDFs and then none will load regardless of size.

Thanks,

Marla

@Marla Smith Miro fixed an error in the console relating to the external library it used when uploading PDFs.   I was able to upload my PDF (which had six content filled pages and one blank page at the end) but could only scroll to the sixth page.   Miro won't be able to load that blank page since it is only part of the metadata of the document and not an actual page.

Miro advises that you may need to log out and back into Miro to ensure you are on the latest version of client.  I primarily use the desktop client on my iMac.  When I open the PDF as a standalone document, the Preview shows all seven pages.  

I tested the PDF in Notion which displayed six content filled pages and Evernote which displayed all pages.  

I would advice trying them in other apps.

I consider my problem fixed because I can upload and view this “problem” PDF.  More data points Miro Support gets the better for the Dev team to analyze.

Coincidentally, I just closed my Request #194426 with Miro Support just before I saw your question.  So ask for Garret.  

Air Elbow Bump,
¯\_(ツ)_/¯ 
Tom.