📰 Dev.to · Nico Reyes

Spent two days manually checking commits. Git bisect found the bug in 20 minutes.

Python multiprocessing crashed because my custom class wasn't pickleable. Here's what I learned fixing it.

How I dealt with aggressive CAPTCHA protection while scraping - the solutions I tried, what failed, and what actually worked.

My CI pipeline passed everything. Production was broken. The route was never registered. Tests mocked the service layer so they never caught it.

Built a link checker for my blog. Missed broken URLs behind redirects. Took a weekend to fix what clicking manually could've done in 2 hours.

I spent 4 hours trying to validate function arguments properly. Here's what kept going wrong.

Let my feature branch drift for 3 days. Had to resolve 47 commits worth of conflicts. Here's what I learned about syncing with main regularly.

CSV quote marks corrupted 2,000 product records silently. Here's what actually happened and how I fixed it.

Docker said both containers were healthy. My app couldn't reach the database. Took 4 hours to find out they were on different networks.

OAuth token expired mid-sync and silently failed. Took 2 hours to figure out why the CRM to email platform sync was half-working.

Python's mutable default arguments bit me in production. Took an hour to find a one-line fix.

Automated my freelance expense categorization with a simple Python script. Saves 2+ hours per month.

Container worked internally but refused external connections. The fix was changing 127.0.0.1 to 0.0.0.0.

Docker container kept crashing with code 137. Turned out to be one character in my config file.

Got 401 errors for 3 hours. My API key was valid. The docs buried the one detail that mattered.

Tests passed but production broke. Here's what my perfect mocks missed.

Went from 4.2GB to 287MB by switching base images and fixing what I copied. 35 minute deploys became 2 minutes.

CSS selectors broke my scraper overnight. Here's how I made it more resilient to website changes.

Timezone confusion with Python datetime caused production scheduler to run 5 hours off. Here's what fixed it.

Automated monthly Slack message archiving to avoid hitting the 10K message limit on free tier.

Built perfect data validation. Then 400 products showed $0.00 because zero is technically a valid number.

Offset pagination broke halfway through my API integration. Cursor based pagination fixed it.

Git merged two feature branches without conflicts. My authentication code disappeared. Here's why it happened and how to avoid it.

Deployed a scraper to production and got instant 403 errors. Turns out User-Agent matters more than I thought.