Function 'fixBOM' finished with error! Unexpected token '<'"

An error like the picture occurs when registering an image with WordPress. I thought there was an error because there was a special character in the image file name, but this error occurs even if the file name does not have a special character. This error does not always occur, it occurs randomly. I want to know why. Of course, I want to know the solution. Please let me know the solution because other people are also experiencing errors

Hello @Reo1,

Welcome to the Make Community!

“<!doctype” is the beginning of an HTML file when the module is expecting JSON.
If you can get access to the entire HTML, it may be an HTML page describing an HTTP error code from a request you attempted to make elsewhere in the scenario.