Yup, twice.
1)The clerical error from office that issued the warrant.
2)The color blind error on the part of the officers (plural) who couldn't tell a white man from a black man.
(talk about a "color-blind society")
How did Brown's name, DOB, and SSN appear on the warrant? Is someone impersonating him? The wrong address is common because crooks move around, and the Marshalls can't be faulted here.
If who ever is impersonating Brown is white, then a clerical error was made by listing him as black.
There is also the possibility that the other Nicolas Brown IS black, and that no clerical error was made regarding race.
The reason the Marshalls showed up at Brown's house is that they have access to a huge data base and the data base matched him with the address, DOB, and Social Security number on the warrant. Prior to service of the warrant, the Marshall's should have had a photo of their suspect. Can we agree, that they probably didn't? Did the originating agency fail to supply one? Looking at the warrant, and not having a photo but seeing that the rest of the identifying information was correct, they could assume that a clerical error was made, and the error was that it listed him as black instead of white. They put him in "custody" and released him later. "Custody," as you are aware, means being in handcuffs, being placed in a police vehicle, being at the police station or jail, or being in a situation where he was not free to leave.
The article doesn't make it clear if he was booked into jail, detained at home in handcuffs for a while, or taken to another location until they got the correct information.