If you have received a File Error message due to using Registration Black in your design, you will need to correct this issue before we can proceed to production.
Registration Black is too heavy/dense of ink coverage for printing artwork - it will take an extremely long time to dry properly which will make smudging a very high risk.
If you are looking for black that offers a rich and dense appearance, you should use our recommended values for Rich Black: CMYK 60, 40, 40, 100.
If your Black is used for small text or gradients, you may want to use 100K Black (CMYK 0, 0, 0, 100).
See: Recommended black colours