So if I understand this correctly, it was a hard fork in version 0.15 (by the definition 'accepting a subset of blocks than a previous version'), but nobody exploited it. Similar the BDB/LevelDB incident documented in BIP 0050 (which actually had a chain split).[1]
There was a chain split due to a soft fork in 2010: the "value overflow incident".[0] Controversial since the soft fork was announced after the incident was exploited.
There was a chain split due to a soft fork in 2010: the "value overflow incident".[0] Controversial since the soft fork was announced after the incident was exploited.
[0]: https://en.bitcoin.it/wiki/Value_overflow_incident
[1]: https://github.com/bitcoin/bips/blob/master/bip-0050.mediawi...