Troubleshooting · Oct 2026 · 2 min read

How to read a stack trace

A stack trace looks intimidating, but it is a map to the problem. Read it in the right order.

Start with the error type and the message. They tell you what went wrong, such as a missing value, a file that could not be found or a type that did not match. Read the message slowly; it is often more specific than it first seems.

Find out which way your language prints the trace. In Java and PHP the most recent call is at the top. In Python the trace says most recent call last, so the actual error is at the bottom.

Look for the first line that points to your own code rather than to a library or framework. Library frames show where the error surfaced; your frame usually shows where it started.

Read the file name and line number, then look at the values involved at that point. Ask what the code expected and what it actually received.

Some errors wrap other errors. Look for sections such as caused by or previous exception. The original cause is usually the last one in that chain, and it is the one to fix.

When you ask for help, send the whole trace as text, not a cropped screenshot. The part you leave out is often the part that matters.