Administration Tool Pages Are Not Available During a Switch Between Read-Only and Read-Write Mode
I was updating our CFS license for one of our Sitecore instances and after I re-indexed a single tree (as what the instructions say to update the CES) something odd happened to the CES instance, when I view the Admin page in CES it always shows me this message ("Administration Tool Pages Are Not Available During a Switch Between Read-Only and Read-Write Mode"). It stays on this page for quite sometime and then refreshes to show the 'normal' admin page after which it toggles back and vice versa. I have restarted the services a number of times already, and in Sitecore, it reports that the CES is unavailable. This CES is shared with a number of other Sitecore clients. What am I missing?
When an indexing action is performed, the licenses in Sitecore (CFS) and Coveo will be synchronised. The license modification will trigger a RO/RW switch once. In you case, you mentioned having multiple CM instances plugged on the same Coveo correct?
If a license is changed on one CM, but not the other, than the license will constantly switch between instances. Usually, when a Pro or Enterprise license is shipped, it is valid for all servers in your farm. So simply make sure that all of your CM servers have the same license. For CD servers, make sure that the indexing strategies are disabled. This is part of the additional steps for CD deployment of this guide.
If you have multiple Sitecore CMS from different projects with different licenses on each, then please contact Coveo Support and they will look at your setup.