How I Debug When I Don’t Even Know Where the Bug Is

One of the most stressful moments as a software engineer is this:

Something is broken.
There’s no clear error.
And you don’t even know where the problem is.

Early in my career, this situation used to panic me.
Now, it still frustrates me—but I no longer freeze.

This post is about how I debug when I have no idea where the bug is, especially in fast-paced startup environments.

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Why Debugging Felt Impossible at First

When I started, I thought debugging meant:

• Finding the error line
• Fixing it quickly
• Moving on

But real-world bugs don’t work like that.

Most bugs are:

• Silent
• Side effects of another change
• Caused by assumptions
• Spread across multiple layers

Frontend, backend, database, network—everything is connected.

This is where most freshers struggle.

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The Biggest Mistake I Made While Debugging

I used to guess.

I would:

• Change random lines
• Restart the server multiple times
• Comment out code hoping it works
• Panic-scroll StackOverflow

This didn’t just waste time—it made things worse.

The turning point came when I stopped guessing and started thinking in systems.

(This shift is similar to the moment when backend finally clicked for me →
https://dailydevnotes.in/when-backend-finally-clicked-for-me)

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My Debugging Rule #1: Assume Nothing

Now, when something breaks, my first thought is:

“What do I know is working, and what do I know is not?”

Not what I assume.

This one change removes a lot of mental noise.

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Step 1: Reproduce the Bug (Always)

Before touching code, I make sure:

• I can reproduce the issue consistently
• I know when it happens
• I know what triggers it

If you can’t reproduce a bug, you can’t debug it properly.

This habit alone saves hours.

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Step 2: Narrow Down the Surface Area

When I don’t know where the bug is, I divide the system into layers:

1. UI / Frontend
2. Network (API call)
3. Backend logic
4. Database / data
5. Environment / config

Then I ask one question at a time:

• Is the request being sent?
• Is the response coming back?
• Is the data correct?
• Is the logic behaving as expected?

Debugging is about elimination, not discovery.

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Step 3: Logs Are Not Optional

Earlier, I saw logs as noise.
Now, logs are my first tool.

I add logs to answer specific questions:

• Did this function run?
• What value reached here?
• Did this condition pass?

Not random logs—intentional logs.

This habit came naturally once I started working in startups where debugging under pressure is normal
(lessons I shared here →
https://dailydevnotes.in/one-year-startup-software-engineer-lessons)

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Step 4: Follow the Data, Not the Code

One of the most important shifts I made:

I stopped following files.
I started following data.

I trace:

• Where data comes from
• How it transforms
• Where it gets lost or corrupted

Code structure matters, but data flow tells the truth.

This is when debugging becomes logical instead of emotional.

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Step 5: Check What Changed Recently

Most bugs are introduced by:

• A recent commit
• A config change
• A dependency update
• A small “harmless” tweak

This is where GitHub becomes extremely important.

Looking at commit history often reveals the issue faster than reading code
(which is why GitHub matters more than people think →
https://dailydevnotes.in/importance-of-github-for-software-engineers)

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Step 6: Reduce the Problem

If things still don’t make sense, I simplify:

• Remove conditions
• Hardcode values temporarily
• Isolate the logic
• Create a minimal test case

If the bug disappears when simplified, I slowly add things back.

This tells me where the issue lives.

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Step 7: Stop Debugging Alone for Too Long

This was a hard lesson.

Debugging alone for hours doesn’t make you strong—it makes you blind.

Now I ask:

• “Can someone sanity-check this?”
• “Am I missing something obvious?”

Fresh eyes often see what tired eyes miss.

This is not weakness.
It’s professional behavior.

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How My Debugging Mindset Changed Over Time

Earlier:

• Panic
• Guessing
• Frustration
• Self-doubt

Now:

• Calm
• Structured
• Curious
• Confident enough to say “I’ll figure this out”

This confidence didn’t come from knowing everything.
It came from repeating the debugging process enough times.

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If You’re Early in Your Career, Remember This

Debugging is not about speed.

It’s about:

• Thinking clearly
• Asking the right questions
• Trusting the process
• Staying calm when nothing makes sense

The day debugging feels less scary is the day you start becoming a real engineer.

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External Resources That Actually Help (No Fluff)

These helped me understand debugging better over time:

• Google Engineering Practices – Debugging mindset
  https://google.github.io/eng-practices/review/developer/debugging.html
• Chrome DevTools Debugging Guide
  https://developer.chrome.com/docs/devtools/
• Postman API Debugging Basics
  https://learning.postman.com/docs/debugging-and-troubleshooting/

Use them as references, not crutches.

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Final Thoughts

If you’re stuck debugging something right now:

Pause.
Breathe.
Structure the problem.

You don’t need to be fast.
You just need to be methodical.

That’s how debugging stops being scary—and starts being a skill.

— Irshad