What is the common syntax error in the provided PHP script?

The common syntax error in the provided PHP script is the missing semicolon at the end of the echo statement. In PHP, each statement should end with a semicolon to indicate the end of the statement. To fix this error, simply add a semicolon at the end of the echo statement.

// Incorrect code with missing semicolon
echo "Hello, world"
```

```php
// Corrected code with added semicolon
echo "Hello, world";