EC
Encoding::InvalidByteSequenceError
RubyERRORNotableEncoding

Byte sequence is invalid in source encoding

Quick Answer

Use encode with invalid: :replace or String#scrub to sanitise invalid bytes rather than letting them raise.

What this means

Raised when a string contains bytes that are invalid for its declared encoding. Common when reading binary data, legacy files, or network responses that are not properly tagged with their encoding.

Why it happens
  1. 1Reading a non-UTF-8 file without specifying the source encoding
  2. 2Receiving raw binary data over a socket and treating it as UTF-8

Fix

Scrub invalid bytes

Scrub invalid bytes
safe = raw.scrub('')          # removes invalid bytes
safe = raw.scrub { |b| "\x#{b.unpack1('H*')}" }  # replace with hex

Why this works

String#scrub replaces or removes byte sequences that are invalid in the string's current encoding.

Code examples
Reproducing the errorruby
"ÿþ".encode('UTF-8', 'UTF-8')
# Encoding::InvalidByteSequenceError: "ÿ" on UTF-8
Safe encode with replaceruby
clean = str.encode('UTF-8', invalid: :replace, replace: '?')
String#scrubruby
clean = str.scrub   # replaces invalid bytes with U+FFFD
Sources
Official documentation ↗

Ruby Core Documentation

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