Is there a recommended process to update the hotspot web files from an older version. I suspect that this is not done through a normal RouterOS update. I seem to be getting client errors after an update to the latest version of 6.34.3.

A customer is reporting that they are receiving an error : upload Javascript using their Samsung S6 Edge phone.

I suspect this has something to do with the md5.js Javascript file and would like to upgrade it.

only if you customized the login page file. if you did not manually override the "html directory" setting, the files should be upgraded together with routeros.