Message
Invalid UTF-8 string. Found a lone surrogate at index $index.
Placeholders (index) are filled from the error’s context. Paste the base64 argument below to see the real values.
What it means
Encoding and decoding bytes: wrong sizes, out-of-range numbers, enum discriminators, sentinels, invalid strings.
What to do
- Match the codec exactly to the on-chain layout: integer width, endianness, prefix sizes and option encoding.
EXPECTED_DECODER_TO_CONSUME_ENTIRE_BYTE_ARRAYusually means the decoder is for a different account version.