This File Error is given by our Prepress team if one or more elements in your artwork are set to overprint.
Overprinting refers to the process of printing one colour on top of another.
The opposite is "knock out": when two objects of different colors overlap one colour is knocked out - this means they will not print on top of each other.
Overprinting will not preview in a PDF file. White objects that are set to overprinting will not print, so it is always best to check that no objects are set to overprint. Using “multiply” has a similar effect as overprinting without the preview issue.
Turning Off Overprint in Illustrator
To turn off overprint, please select the object in Illustrator then go to Windows/Attribute to open the Attribute window - make sure that you turn off (uncheck) the Overprint fill and Overprint stroke boxes.
Turning Off Overprint in InDesign
To turn off overprint, go to the drop-down menu "Window > Output > Attributes" to open the Attributes window - select the object(s) and then make sure that you turn off (uncheck) the "Overprint Fill / Overprint Stroke" boxes.
You should also ensure that you have turned off 'Overprinting of Black' in InDesign.
Go to the drop-down menu "InDesign > Preferences > Appearance of Black", and then make sure that you turn off (uncheck) the box for "Overprint [Black] Swatch at 100%".
