I have the same error playing Historic Pauper. I have the following line in the log:
Error response for message. {"id":62,"code":6900,"message":null,"data":"{\"eventName\":\"Historic_Pauper_20191128\",\"validationErrors\":[\"Too many copies of a specific card: titleId 763\"],\"deckName\":\"Black\",\"format\":\"HistoricPauper\"}"}
I have the same error playing Historic Pauper. I have the following line in the log:
Error response for message. {"id":62,"code":6900,"message":null,"data":"{\"eventName\":\"Historic_Pauper_20191128\",\"validationErrors\":[\"Too many copies of a specific card: titleId 763\"],\"deckName\":\"Black\",\"format\":\"HistoricPauper\"}"}