The link for the main curseforge page is outdated used on the optional client mod's curseforge page is outdated.
the optional client mod's link still leads to
http://minecraft.curseforge.com/mc-mods/74735-forge-essentials-74735/

The correct link is actually this
https://www.curseforge.com/minecraft/mc-mods/forge-essentials-74735/
I suspect you merely forgot to update to update the link after curseforge changed navigating url's to what it is now.

Thanks? Not clear is which page is now outdated as I followed both your links. Indeed the second one lands on the correct page for the main mod but can you clarify where the supposed wrong link is posted?

This text/link from the client mod's page is pointing to curseforge's old url format, which doesn't work anymore.

For more information about the ForgeEssentials project, visit our main CurseForge page.

You need to update the link's url to this, as it's the current url of the main mod in curseforge's new/current url format.
https://www.curseforge.com/minecraft/mc-mods/forge-essentials-74735/

Thanks for the tip... I never noticed that the old link didn't exist.