this is ridiculous I paid way too much to have to deal with this glitch or bug in that keep giving me the ERROR msg; you cannot install this plugin as there are no compatible engines
by the way i was being generous in the title, because it’s almost ALL of THEM!!!
is this the only way to get tech support?
I don’t know what plugins you’ve purchased but it’s possible that they are not being kept up to date with the latest versions of Unreal.
If you have the source of the plugins you purchased then you will probably have to rebuild them yourself against the Unreal version you are using. Otherwise you’re probably best off contacting the developers who made the plugins for support.
If you choose to try fixing the plugins yourself, posting the specific error messages (Or screenshots of them) here will allow others to help.
As for options for getting tech support, the ones I know of are this AnswerHub, the Unreal forums, or the Unreal Developer Network (UDN). I’m pretty sure you have to pay to access the UDN though.
Epic is not developing the Plugins. It is a marketplace for other developers to sell there plugins. So if you need support, I guess you only have the chance to contact the devs directly. Don’t use the Review section or something in the launcher, the seller will not get a notification. But on every plugin there needs to be a support URL or a Mailcontact or something.
As far as I know it can always take some time when a new Version is released, because of the Dev need to compile and test against the new version of UE AND the more important thing - he/she needs to submit it to EPIC and it goes through a Review and QA Process - this takes also time he can’t influence.
When it is not a C++ Plugin, simply install it for the latest version it is available and Copy the Content of the Plugins/YourPluginName from the old Engine installation foldert to the new one - or better, to the project folder you are using it which is in the newer version. Even when it is C++ plugin this works most of the time, because you have the sourcecode as part of the plugin and when opening the project it justs recompiles. I haven’t seen anything really being fully broken for quite a long time.
But to shorten things - I personally would punish the seller. I allways build my Plugins (not selling on the marketplace but developing for customers) against the latest Release Branch and Promo Branch from GitHub. Currently I’m testing my work against 4.23 and 4.24…so there is always a way to provide quality work if you like and if your clients pay for the additional effort 
@Punitiate yes UDN is payed. but you also get a one-to-one person on epic side for support questions by mail for example. Answerhub and Forum is nealy 100% community driven, except maybe legal questions and bug reports for the current build…