PDF file was altered after being uploaded to Dropbox

[MartyF9]

I have recently discovered that when I have uploaded a PDF to be shared with others, there are changes that occur with the PDF that are not present in the original.

For example, I noticed a strange bit of a shaded area on one page and when the printers download the file, the colour profile for the PDF is different to the original. This results in incorrect representations of the document when printed.

I tested this by uploading the exact same file to Onedrive and these changes did not occur and the file printed perfectly by the printers.

How is it possible that uploading a file to Dropbox can alter the PDF?

Extremely odd.

[Hannah]

Sorry to hear about this, @MartyF9.

Are you uploading this file to your Dropbox account through the website?

How does it preview for you on the website, does it look altered in your account, or does it get altered only when you share it?

And are you sharing it through a Dropbox link?

Let me know and we'll go from there.

[MartyF9]

Thank you for the reply.

1. I uploaded the PDF via the website
2. I was informed by one member who I had shared the PDF with that they found an error which was not visible in the file on my computer. They did a screen shot which confirmed what they were saying. Unfortunately I do not have that same file any longer.
3. And yes, I was sharing it via a Dropbox link.

The PDF file and previous ones where there were issues tend to be about 140 MB +

I had checked the last file I uploaded and viewing it on-line and downloading it seem to be OK.

Perhaps this was a glitch on this occasion or maybe the shared user had gone into edit mode. I cannot be sure.

Just as a bit of extra information, the PDF is in CMYK with a generic CYMK color profile. Also, the printers had to increase the brightness by 4X for it to print correctly whilst the last copy where I did not use DropBox, they did not need to increase the brightness. The settings for the PDF creation had not changed.

[Jay]

Hi @MartyF9, are the changes visible after downloading the file from the shared link, or only when viewing on the website?

Did you print the file from the site, or after downloading it to your computer?

[MartyF9]

I will need to check with the user that pointed this out.

It was not printed at the stage that the errors appeared.

I will get back to you when I get further information.

[Jay]

Thanks, keep me posted with any updates!