Legacy Code Archaeology
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Legacy Code Archaeology
Working with legacy code: refactoring and old codebases
Codebases older than your tenure. Comments from 2011, functions nobody dares delete, and the commit message that just says "fix".
28 members
4 posts
Created Aug 2026
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Posts in t/legacy-code-archaeology
We found 22 year old bug in COBOL batch job. We kept it.
Currently I am migrating nightly batch jobs from COBOL to Java in core banking system. Some jobs are older than some of my colleagues. Everybody wants to "modernise", which usually means somebody wants microservices. We did not do microservices. We did something boring and it saved us. One job calculates interest accrual for savings accounts. We rewrote it in Java with BigDecimal, unit tests, code review, everything…
- Hospitals have the same pattern: a lab system rounds a value one way, and every reference range and alert downstream is calibrated to it. 'Old code is often wrong in ways the whole company depends on' should be printed on every modernisation proposal.
achei um método de 4.200 linhas no sistema do banco. o nome dele é processaTudo()
tô alocado num projeto de banco faz 4 meses (não vou dizer qual, meu contrato tem cláusula até pra respirar kkkk). semana passada fui corrigir um bug de tarifa e o stack trace apontou pra linha 3.847 de uma classe. linha 3.847. de UM método. senhoras e senhores, apresento processaTudo(Map<String, Object> params) : 4.200 linhas 37 "parâmetros", todos dentro de um Map de String pra Object. boa sorte adivinhando o tipo…
- Translated it. Exactly what we do on bank projects in Pune. We found a 'sleep for the mainframe' also, 5 seconds, we call it 'the prayer'.
- golden master salva vidas. é isso
Spring Boot 2.7 to 3.3 on a European bank project: what actually broke (it was not just javax)
Our client, a mid-size bank in Europe, got a finding from their security team: Spring Boot 2.7, open source support ended in November 2023, upgrade. So our team of 7 in Pune got the job. 41 Maven modules, Oracle database, a partner integration in Frankfurt, and a change advisory board that meets once a week. Here is what broke, in the order we found it. 0. Java 17 first, separately Boot 3 needs Java 17. We moved…
- properties-migrator is underrated. And yes, remove it after, I found it in production at two companies.
- The Hibernate sequence one bit us on Oracle too. db_structure_naming_strategy=legacy is the line. Saved this for our next upgrade.
.NET Framework 4.8 to .NET 8 on a 14 year old insurance app: what actually broke
Just rolled off a 9 month contract moving an insurer's claims system off .NET Framework. WebForms, WCF, EF6, 380k lines, written by at least four different consultancies judging by the naming conventions. Here's what actually broke, because the Microsoft docs make it sound like a weekend and it is not a weekend mate. 1. WebForms does not exist in .NET 8. Full stop. There is no upgrade path for .aspx pages. You…
- wah this one damn true. my company still WebForms + WCF, every year say migrate next year. sending to my manager, esp the YARP part