Problem when printing PDF document of EP1508424A1


A user reported that he wasn’t able to retrieve the document PDF of EP1508424A1 properly. While all drawings look fine, all text is distorted after printing, see EP1508424A1.pdf (1.6 MB).



After checking back with [1] and [2], we found that while both PDF documents render flawlessly on screen, the printout is distorted when printed directly from the Browser.

However, when downloading the PDF document first and then sending it to the printer from your operating system, the printout is totally fine.


Primary investigation

We found that when downloading the PDF documents and printing them from your local operating system, everything works as expected. Text only becomes distorted when printing directly from the Browser.

As we have been able to confirm this behavior with Firefox, we filed a corresponding issue at pdf.js:

Further investigations

We got a positive answer already. A bug (#1524640) has been fixed recently which resolved an issue with font loading when printing [directly] from Firefox. Thanks, Tim van der Meij!

Works in upcoming releases of Firefox

Coming from there, we have been able to confirm that printing the corresponding PDF documents directly from Firefox works flawlessly again with Firefox Nightly ¹.

Firefox Beta 66b12, which is widely available from Download the Firefox Browser in English (US) and more than 90 other languages, should also work, so we are providing some quick download links here:

¹ Firefox Nightly was installed on macOS by executing:

brew tap homebrew/cask-versions
brew cask install firefox-nightly




1. Wait for Firefox 66
The upcoming release of Firefox 66 which will ship on March 19, 2019 most likely mitigates this issue as we have been able to confirm using the current Firefox Nightly.

2. Install Firefox 66 Beta
Firefox 66 Beta, Revision 12 should already be sufficiently mature.


1. Explicitly request PDF from OPS
By going to “External sources » PDF and Images » OPS” through the context menu on the right side of the document header bar


you can explicitly request the PDF document from OPS, see also Problem when accessing PDF document of EP2706864A2.

2. Download PDF before printing
If you are not able to install a recent Firefox Beta release on your machine, please work around the problem by downloading the PDF documents before printing, e.g. by using the bulk download option as outlined on Auswahl an Druckschriften-PDFs herunterladen.


Firefox 66 is around the corner and the problem will most likely go away by simply upgrading.
Please enjoy your research and sorry for the inconveniences this might cause to you and your colleagues.