What was wrong with block 74638?

[BlackHatCoiner]

Back on August 15, 2010, someone generated 92233720368.54277039 bitcoins due to a bug. What was exactly the bug and how did they fix it? As far as I know, since a transaction is confirmed, it cannot be changed unless someone redoes the proof of work. The next block was mined 2 minutes after that one, so how did they do it?

The coinbase transaction that was moving all these bitcoins was hashed in order to be on the block so if they "simply changed" the 92233720368.54277039 to 50, it would return a completely different merkle root. Therefore, all the next blocks would be considered as invalid.

[NotFuzzyWarm]

Someone does not know how to use a search engine?
Simply searching for "92233720368.54277039 bitcoins"  or "block 74638" returns http://blog.theshayan.com/2017/12/01/once-there-were-184-billion-bitcoins/ as the #1 hit on Google with the full history of what happened...

There is also a WIKI about it

In short it was an overflow bug which the Core devs very quickly caught and and acted upon as soon as the 2 Tx's happened. In response they did a soft-fork rollback within 5 hours of the incident to nullify the transactions.

[FinneysTrueVision]

They fixed the bug and the majority of the hashrate switched to the new client which rejected this transaction. This created a fork and eventually the side that didn't have this transaction became the longest chain and all the nodes accepted it as the official version of the blockchain.