History of OP_RETURN

Bitcoin Core

The history of OP_RETURN relay limit in bitcoin core

before v0.9.0 (Oct 2013) - allow a single OP_RETURN of up to 80 bytes

v0.9.0 (Feb 2014) - limit reduced from 80 to 40 bytes

v0.10.0 (Sept 2014) - variable moved from src/scriptutils.h to src/script/standard.h

v0.11.0 (Nov 2014) - limit increased from 40 to 80 bytes

v0.12.0 (Oct 2015) - limit increased from 80 to 83 bytes

v26rc1 (Aug 2023) - limit moved from src/script/standard.h to src/policy/policy.h.

At least as early as v0.12.0-knots (Feb 2016) - limit set to 42 bytes.

What has caused significant confusion is that Luke has forked core at multiple times, meaning he has to re-do some of his previous changes.

For example, in May 2022 - limit reduced from 83 to 42

Oct 2013 - allow a single OP_RETURN of up to 80 bytes

Feb 2014 - limit reduced from 80 to 40 bytes

Sept 2014 - variable moved from src/scriptutils.h to src/script/standard.h

Nov 2014 - limit increased from 40 to 80 bytes

Oct 2015 - limit increased from 80 to 83 bytes

May 2022 - limit reduced from 83 to 42