EVE Online begins massive migration to Python 3

EVE Online is upgrading its 2.4-million-line codebase to Python 3 after 16 years on the same language version.

Developer CCP Games announced the space MMO is migrating off Stackless Python 2.7, a release from 2010 that reached official end of life back in 2020. The team started Stage 1 of the multi-phase transition, using automated tools like Python-Future to make the existing code Python 3-ready.

Why it matters: Staying on unsupported tools costs engineering time that could go toward shipping new features. Moving to Python 3 gives developers modern profilers, faster execution, and cleaner string handling, keeping a 23-year-old game maintained without interrupting its 23.75-hour daily uptime.

Know this: Fixing broken syntax is only step one. An initial compiler scan showed 95.9% of EVE’s ~20,000 Python files already compile under Python 3, leaving roughly 3,300 blocking lines with obsolete patterns like 123L long literals. The harder task is Stage 2: reviewing ~20,000 lines of code that compile in both versions but output different results. For example, integer division 1 / 2 returns 0 in Python 2, but 0.5 in Python 3. Because those calculations control damage numbers, coordinates, and player ISK, developers have to inspect each one manually.

If the engineers succeed, the largest code migration in EVE's history will be completely invisible to players.