I'm guessing that there is something specific to your workbook which is causing an issue. For example: "Response code: 500, Tableau Server encountered an unknown error" Error | Tableau Software
Do you have the same issue if you try to publish a different workbook?
I'm getting the same error message. The workbook was working and then when I added more tabs and now it doesn't.
Response code: 500
Tableau Public encountered an unknown error.
The only thing that worked for me was to upload it as a new workbook under a different name.