Based on the most recent Mozilla updates, the ESR version of Firefox is 52.8.0.
But PatchMyPC wants to install what it believes to be a 60.0 ESR version.
There are Firefox ESR 60.0 & 52.8
ESR 60.0 is the new one and will continue for a long time. 52.8 will be discontinued next month.
https://wiki.mozilla.org/Release_Management/Calendar
Thanks for the info. Based on the calendar you linked to, Firefox 52.8 ESR will be replaced by 52.9 ESR this month. Discontinuation won't occur until early September, it seems.