Photos with Craigslist - Cannot upload images

I cannot upload pictures to Craigslist from Photos. I was able to do this with iPhoto under Yosemite, but now it just hangs up the Craigslist upload page.... NOT very practical... Any ideas? Does this require some sort of plug-in? (though apparently Photos can't accept plug-ins...)

As much as Apple used to represent a seamless customer experience, all new upgrades now signify a significant step backward.... (iPhoto versus Photos, what a downgrade..!!!) With Windows you dread the Blue Screen of Death, now with El Capitan you have the pinwheel of terror.

Frustrated,

Denis