'utf-8' codec can't decode byte

This error message usually occurs when a program is trying to read a file or a string that contains characters that are not encoded in the UTF-8 format. UTF-8 is a character encoding system that is widely used for storing and transmitting text data.

To fix this error, you can try the following:

1. Make sure that the file or string you are trying to read is actually encoded in UTF-8. You can use a text editor or a command-line tool to check the encoding.

2. If the file or string is not encoded in UTF-8, you can try to convert it to UTF-8 using a tool or library that supports character encoding conversion.

3. If you are working with Python, you can use the built-in `open()` function to specify the encoding of the file you are reading. For example, you can use `open('file.txt', encoding='utf-8')` to read a file that is encoded in UTF-8.

4. If you are working with a different programming language or tool, consult the documentation or seek assistance from the community to find the appropriate method for handling character encoding.