The Formatexception error is usually thrown when there is an issue with the format of a string. In this case, it appears that the string being passed to the function is not in the expected format and there is an unexpected character at the first position.

To fix this issue, you need to identify the source of the string and ensure that it is being formatted correctly. This could involve checking the code that generates the string or the data that is being used to create the string.

Once you have identified the issue with the string’s format, you can modify the code or data to ensure that the string is correctly formatted and the error is no longer thrown.