You have probably already seen this in the news already but vSphere 6.7 Update 1 has now released to download. Link Is below in case you need it:
vSphere 6.7 Update 1 Download Link
Also to get a bit more info on whats under the hood on the updated vSphere web client i would recommend the following:
So far VEEAM is the only thing ive heard so far that has an issue: https://www.veeam.com/kb2784
Had an interesting one the other day, deploying windows 2016 servers for a customer, setting one up as a jump server for support staff i naturally wanted to check that we could access the vSphere web console correctly using both flash and html variants.
By reading this post you can imagine that it didn’t work due to our old friend flash. However there is an easy fix
dism /online /add-package /packagepath:"C:\Windows\servicing\Packages\Adobe-Flash-For-Windows-Package~31bf3856ad364e35~amd64~~10.0.14393.0.mum"
Running this will get the respective flash component installed to enable you to use the web client again. More details are available at Technet Article