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Michael Tharrington
Michael Tharrington Subscriber

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What's the biggest mistake you've ever made while coding?

I really enjoy reading posts where authors talk through a mistake that they have made and what they learned from it. I find these posts to be really relatable and enjoyable to read. It's nice to hear someone teach you something from a place of humility, and when folks are talking about the lessons they've learned from their own mistakes, they often have an empathetic, approachable tone.

So, with that in mind, what's the biggest mistake you've ever made while coding?

What problems did your mistake cause? How did it happen? And, what did you learn from it?

Top comments (38)

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ben profile image
Ben Halpern

I have made mistakes I hope to never make again.

I have:

  • Deleted production data
  • Pushed some code which actually caused a system-wide infinite loop in the cloud environment. My bug showed up in their status page πŸ˜†
  • Made a change which took down DEV for 10+ hours

Harder to sum up, but I've definitely made software design choices which caused problems later, and are still causing problems today. The notorious technical debt.

All of these experiences give me caution which I hope to pass on to others, but it's also important to know that some mistakes are not overly avoiding. As they say in CSS, if everything is !important, nothing is !important. I think mistakes related to data and privacy are the top mistakes to avoid. Any mistake with a known remedy or short-lived impact are not dramatically worth avoiding.

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ant_f_dev profile image
Anthony Fung

I had a colleague once who dropped a table of data from live. Luckily it was a relatively new system :)

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parenttobias profile image
Toby Parent

So back in the day, I was working for a tech startup in Boston's metro-west area. I was one of the front-end devs, and we were building some great tech that was being fed a transcript via an API. But the boss wanted to get experimental.

"Wouldn't it be great if, as we progress through the transcript, we could pop up related material at a particular time? Say, the transcript mentions Steve Jobs, we pull up his Wikipedia profile and the top five news stories, or it mentions Microsoft, we display their stock ticker, business news, and related content on the fly?"

And yeah, that sounded neat. But let's be real - it was 2007.

So I tried, I found a great early BaaS from Yahoo! called Pipes. Way ahead of its time, but it allowed us to scrape, munge and combine feeds, based on what we passed to a call to a particular pipe. It was a meta-API, of sorts.

So yeah. The first few days of playing with the parts, things were looking very promising. The Pipe was working as I wanted, it could handle different types, it could return different data, and I could consume it however I like. Sweet!

And then at scale. From the live transcript. That's where I broke things.

See, in one way you can take a particular key term at a particular point in time, pass the request, get the data. With a very small change, you can take all the key terms, from all the points in time, and request them all. For each key term. Thousands per minute.

I inadvertently used Yahoo! for an ugly sort of DDoS on multiple search engines and sites. Boss and I had to go to a meeting with numerous tech heads, explain what our code did and why - they were more curious about the use case and the "how and why", and less about blame.

Honestly, I think we learn more from those moments someone breaks stuff.

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michaeltharrington profile image
Michael Tharrington

This a great anecdote, Toby! Thank ya for sharing

I inadvertently used Yahoo! for an ugly sort of DDoS on multiple search engines and sites.

Haha! Love it. πŸ˜†

I also love that everyone was more curious about how and why it happened versus trying to put blame on anyone. That sounds like a good, healthy environment to be in.

And I so agree with ya about folks learning lots from those moments when someone breaks stuff. Nothing like a painful mistake to help ya learn something! Said the man who has made many a painful mistake, haha. πŸ˜…

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bad_request400 profile image
Bad Request 400 • Edited

New branch for debugging, pulled from prod and not test. The picture speaks for itself….

Image description

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chrisgreening profile image
Chris Greening

ahhh pain....

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bad_request400 profile image
Bad Request 400

Yep, was an interesting meeting the next day. That was the moment I disabled β€žauto-commitβ€œ on every datagrip installation from then on.

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syeo66 profile image
Red Ochsenbein (he/him)

UPDATE users SET password='...';

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bad_request400 profile image
Bad Request 400

Ah yeah... the plain text passwords.

How i miss them (somewhat).
It was so easy and convenient.
Now every password is hashed before so writing it directly to db is not an option anymore.

Alternate route: Hash Api Endpoint which takes plaintext as body and returns the hash.
Not as convinient but it works :D

so long

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syeo66 profile image
Red Ochsenbein (he/him)

Actually, the passwords were hashed, and I was actually using the hashing function to get the new passwords string... did not help anything in this case. 🀣

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devfranpr profile image
DevFranPR

Is this a mistake or a good way to remind your users to change the password ? 🀣

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syeo66 profile image
Red Ochsenbein (he/him)

Well, we sold it as a security feature to our users... 🀣

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devfranpr profile image
DevFranPR

Wonderful

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chrisgreening profile image
Chris Greening

Lol not nearly my biggest mistake ever but a particularly frustrating (and now funny one) back when I was building my photography section for my personal site:

I don't remember the exact filename but I had a file named something like "3DCssRenderer.js". I was developing locally on Windows and deploying to an Ubuntu server (obv not best idea as we'll learn in a moment but I was being lazy)

The code was working 100% fine on my machine but when deployed to the remote server the 3DCssRenderer.js couldn't be found which wasn't an error I was anticipating

After like 6 hours of tedious debugging I eventually realized the file was named 3DCssRenderer.js (uppercase C) but somewhere I made a typo and something was looking for a "3DcssRenderer.js" (lowercase c).

Windows isn't case sensitive but Linux is hence why it worked locally and not remotely (and of course it was "C" vs. "c" which isn't obvious at quick glance). Sure enough fixed the typo and it worked perfectly after that πŸ˜… This experience has actually helped me a few times now helping colleagues solve similar bizarre bugs

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bad_request400 profile image
Bad Request 400

Oh yeah Case sensitive or Line-Break difference between Windows - *unix Systems is something prob. everyone of us stumbled upon

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chrisgreening profile image
Chris Greening

Case sensitivity was one of those things I "knew" about but hadn't properly internalized until I encountered this error lol line breaks as well, I've def got a painful carriage return story or two floating around somewhere...

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Thomas Bnt • Edited

When I read the question, I immediately thought of starting CSS but on a shit*y foundation. It can't be the worst thing, but it sucks to start all over again when you've made good progress. 😢

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parenttobias profile image
Toby Parent

I do feel that some of the gowns on display at Paris Fashion Week 2023 were the result of some badly-coded CSS: instagram.com/reel/Cn2KL2MMJwE/

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michaeltharrington profile image
Michael Tharrington

lol, these are ridiculous!

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Christine Belzie

I second this @parenttobias! :) Not every design is meant to be "avant-garde". Sometimes, the most fashionable design is the simplest one. :) Lol, can you imagine a model like Naomi Campbell or Shalom Harlow wearing that dress in public? Lol! :)

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Thomas Bnt

ahaha yeah

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sfleroy profile image
Leroy

Not communicating when things started to go off rails from the estimate on a big development.

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fersa profile image
Ferhat

I am not doing this for long, however my biggest mistake so far was to set up a cronjob wrong. Instead of sending an email to all inactive accounts on the 15th of a month it send an email every minute to all inactive accounts on the 15th of the month. Over 300 people received 600+ email from us.

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Anthony Fung

Directly coding wise, I was adding to an enum list and thought it would be helpful to add it alphabetically so you'd see it when scanning the list. This gave the enums different values as they were assigned automatically as incrementing values. Very strange program behaviour followed.

Related to coding but not exactly, I almost lost two weeks worth of work by not know what I was doing in Git

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Eric Donovan

I had some dodgy "retry on network fail" logic in our client android app that accidentally retried twice for each failure (which of course escalated quickly). Tested fine, got pushed to production and then we started getting messages from the server team.

So I basically created a bot army out of our android users and got them to DDOS our own servers πŸ˜‚

That was a decade ago, but to this day I try and avoid any automatic retries. If it's an option, I much prefer to let the user chose to retry manually

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ogoh cyril

πŸ˜‚πŸ˜‚πŸ˜‚ the ending sounds like ptsd

And yep I have been there