Project Online or Project Server - best leave the master pages alone!
Published Jul 11 2019 09:42 AM 5,337 Views

Because some customizations can break Project Web App pages we have always blocked SharePoint Designer from editing/changing a PWA master page - and in the 2007 version I even blogged about it.  Time moves on and there are now new ways to play about with master pages, and new ways to break PWA!  Design Manager was released a couple of years ago to allow easy branding of SharePoint pages, and this isn't something we can block for PWA so it is possible to break our pages - so for the best experience do not update the master pages on a PWA site.

As with any 'unsupported' change that doesn't always mean you shouldn't do it - but just be prepared that it might break something, so test thoroughly and then if you do find a break you will need to either fix it by reverting or further modification.  We can't help you from support to troubleshoot the break - our support only extends to reverting to the original master page. 

The most recent issue I've heard of where a master page caused problems affected some of the charts in the Resource Center - but I'm sure there are many different ways that things might break.

We have added this unsupported scenario to our software boundaries and limits documentation at

Just for reference - the documentation for Design Manager can be found here - 

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‎Jul 11 2019 09:41 AM
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