# Expo Router: find() returns undefined for a dynamic route id

> Everything from the URL is a string. e.id === id compares the number 1 with the string "1" and fails.

Web page: https://davidewins.com/errors/expo-router-params-always-strings

Expo. Confirmed fix, 7 October 2026.

Versions: Expo SDK 57, expo-router 57.0.24

There is no error message for this one, only the symptom in the title.

## Cause

Everything from the URL is a string. `e.id === id` compares the number 1 with the string "1" and fails.

## Fix

Convert before comparing:
```tsx
const exercise = exercises.find((e) => e.id === Number(id));
```

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