EC
Utf8Error
RustERRORNotableString

Invalid UTF-8 in byte slice

Quick Answer

Use from_utf8_unchecked only when you have verified the bytes are valid UTF-8.

What this means

Returned by std::str::from_utf8() when a &[u8] slice contains invalid UTF-8. Provides the error byte offset.

Why it happens
  1. 1Byte slice from a non-UTF-8 source
  2. 2Slice cut mid-character in a multi-byte sequence

Fix

Get error position

Get error position
match std::str::from_utf8(&bytes) {
    Ok(s) => println!("{}", s),
    Err(e) => {
        println!("Invalid UTF-8 at byte {}", e.valid_up_to());
    }
}

Why this works

valid_up_to() tells you how many bytes were valid, useful for partial decoding.

Code examples
Triggerrust
std::str::from_utf8(&[0xFF, 0xFE])?; // Utf8Error
Sources

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