Getting Error: Cookies are blocked due to unexpected output.

solutions mentioned in this discussion might be of help https://www.ads-software.com/support/topic/unable-to-log-in-cookies-are-blocked-due-to-unexpected-output?replies=37

For fix this issue check your log file(debug.log)

When checking your error log file, check the error logs for the date, you started to get the error. In error messages check if it says anything like: “Cannot modify header information – headers already sent by (output started at”) and then go to file path (file path :in debug log file) check where is the issue. some time due to white space end of the file or closing php (?>) tag causes this issue. remove the white space end of the file and check.

More Detail Here: https://www.wpseeds.com/blog/error-cookies-are-blocked-due-to-unexpected-output/