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MAC OS X Sierra was released about 5 days ago... so early updaters may encounter some problems, that's to be expected.
Your printer driver is crashing. Is it a driver only assured to work with a lesser version?
Evidently - it is for 10.10, not Sierra.
If you just bought the printer, and your downloaded driver crashes, try first removing it, then trying the disc that came with the printer (if there was one, and if it at least is compatible up to El Capitan (10.11) -?
Which printer is it, please?
OK. I presume you have tried the Brother USA support site for that model and found no driver for anything more modern than 10.10, correct?
for 10.11 for what seems to be your printer model.
True. Try the 10.11-compatible drivers. See if they work.
Let me know how it goes, please. Thanks.