What does "curly braces deprecated" in PHP mean?

The reason you're getting this error is because the use of curly braces in PHP has been replaced by square brackets. The specific error will be found in the specific line of the file that's mentioned in the error message. You will need to open this file in a text editor and replace the curly brackets in that line with square brackets. You can navigate to the specified line using the vim text editor by following these instructions. Additionally, more information about this error can be found in this Github post, along with this StackOverflow post.