When printing with Safari on either macOS 10.14 Mojave or macOS 10.15 Catalina, some users have reported receiving the following error message printing out:
OFFENDING COMMAND: imagemask
This issue seems to be impacting Safari users when printing through a variety of websites. However, the issue seems to be resolved by simply installing Adobe Acrobat Reader from Adobe's website (the optional offers are not required to resolve this issue).
Alternately, the purchased music can also be printed using a different web browser - such as Google Chrome or Mozilla Firefox - or using our free Musicnotes Sheet Music Player for Mac app.