# Error when uploading pdf for printing
**URL:** https://support.rpgtrader.com/t/error-when-uploading-pdf-for-printing/5349
**Category:** Support
**Tags:** print-on-demand
**Created:** [September 1, 2026, 7:23pm UTC](https://support.rpgtrader.com/t/error-when-uploading-pdf-for-printing/5349 "2026-09-01T19:23:59Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@hzl](https://support.rpgtrader.com/u/hzl)
#### Post date: [September 1, 2026, 7:23pm UTC](https://support.rpgtrader.com/t/error-when-uploading-pdf-for-printing/5349/1 "2026-09-01T19:23:59Z")
Been trying to set up print on demand for my game, and I get the error “Upload failed. HTTP 502.” every time I try to upload my pdf for the interiors. It seems to upload fine, showing the percentage progress all the way up to 100%, then the error happens.
I thought it was user error at first, so I reformatted my pdf several times. But that didn’t work, so I went to Lulu, set everything up there, downloaded the interiors from them, uploaded it here on RPG Trader. That still didn’t work, same error again.
So the problem doesn’t seem to be how I’m formatting it, but I’m not sure what else to try. I tried using a different browser, a different computer, my phone, refreshing the page, and clearing my browser cache, but I get the same error every time.
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### Author:  [@hugh](https://support.rpgtrader.com/u/hugh)
#### Post date: [September 1, 2026, 9:01pm UTC](https://support.rpgtrader.com/t/error-when-uploading-pdf-for-printing/5349/2 "2026-09-01T21:01:16Z")
Thanks for flagging this! We’ll investigate this today and update as soon as we have an answer here.
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### Author:  [@hugh](https://support.rpgtrader.com/u/hugh)
#### Post date: [September 2, 2026, 12:40am UTC](https://support.rpgtrader.com/t/error-when-uploading-pdf-for-printing/5349/3 "2026-09-02T00:40:52Z")
We had a look into this, and it looks like the most likely issue is the file timing out on validation due to size. That’s no fault on your part, but rather how we were processing larger files. We have updated the validation flow to handle large files more efficiently, so this should work now.
Additionally, the error message you see should be more helpful now, instead of a generic “HTTP 502” message.
Refresh the page and try again. If it still doesn’t work, please email your book files to [support@rpgtrader.com](mailto:support@rpgtrader.com) along with any error message you receive and we’ll figure it out from there.
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### Author:  [@hugh](https://support.rpgtrader.com/u/hugh)
#### Post date: [September 2, 2026, 2:16am UTC](https://support.rpgtrader.com/t/error-when-uploading-pdf-for-printing/5349/4 "2026-09-02T02:16:45Z")
Noting here that we have resolved this issue over email. The cause was that the uploaded book uses the comic book size, and we didn’t offer the option fo the 70# coated paper that lulu requires for comic books. We now have this option and comic books will work for all creators going forward.
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### Author:  [@system](https://support.rpgtrader.com/u/system)
#### Post date: [September 4, 2026, 2:17am UTC](https://support.rpgtrader.com/t/error-when-uploading-pdf-for-printing/5349/5 "2026-09-04T02:17:39Z")
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