Will Planner ever work for people with On Prem Exchange?

[Mike Boehm]

We are trying to use Planner but can't add things to Favorites and get other errors.  I was told this is because we use an On Prem version of Exchange.  Is this true?  If so, is there anything in the works to make Planner work for people with On Prem Exchange or do we have to move our Exchange to online before we can get favorites, notifications, etc to work?

[#2]

That is correct. Many of the newer Office 365 apps require your mailbox to be in Exchange Online due to how they are engineered.
It's not to say that it won't work in the future with on-prem, but I doubt it's something even on the horizon.

[#3]

Well, Planner is just a cloud app that for now is not intended to work OnPremises...as you know Planner relies on Groups and while it's true you can sync back Groups to your local AD, this is the only OnPrem integration you have for now

[#4]

When you On Prem Exchange you cannot able to post comments and mark plans as favorites within OWA. But still you can use Planner. 

[#5]

1 year later has there been any progress on getting working with "On Prem" Exchange.  at least for the flow of comments between team members?

[#6]

@Mike Boehm: I'm not sure if this will give you exactly what you are looking for - but I did find a way to have a "Plan" with other members, even though we still use on-perm Exchange. Basically, I created a Team in "Teams", and then added a tab in it and picked "Planner" from the icons. With that "Plan", I was able to assign tasks in that plan to any members of the already created "Team" - which doesn't seem to have any issues with our emails being hosted on-prem. We are running Azure AD Connect to synchronize all our local accounts out to Office 365, so it does have all the account info including AD groups, etc. So basically, I had to encapsulate the Plan in a Team to get around those errors where I couldn't add members, etc. Also, that plan does show up in my Office 365 Planner page, and then I was able to copy each task in a Plan I had already created over to the new teams-based plan. (Although it won't copy attachments or labels when crossing over for some reason - those options are grayed-out, so I had to manually move those parts.)

Hope that is helpful!