Category Archives: pchat

Multiple Lync Persistent Chat pool headaches

Why would you want more than one Persistent Chat pool? We can scale a single pool to 4 active servers each with 20,000 users, to support 80,000 concurrent PChat users – enough for a great many organizations. In many cases, a single central PChat pool makes a lot of sense. With good use of PChat categories, different groups of users can be separated if needed, and administration (such as creating new rooms) easily delegated.

However, this single-pool model doesn’t fit all. Sometimes different regions or countries host their own Lync infrastructure in a shared topology and each will need (or want) their own Persistent Chat pool.

Generally, this works fine but there’s a problem – the dreaded “Your chat room access may be limited due to an outage” message. You may have seen it before if you’ve broken something, but you will also see it if any PChat pool defined in the topology is down.


Your local PChat pool may be up, users may be able to get to their chat rooms, but this can still cause a lot of helpdesk calls. It also looks very similar at a glance to the “Limited functionality” warning, which can impact users’ perception of how reliable Lync is.

There are some practical things you can do to help mitigate this however:

  • Agree patching / outage windows for Persistent Chat pools, to avoid users’ typical working hours (in all regions!)
  • Care and planning are needed when adding a Persistent Chat pool. Ensure at least one server for the new pools is ready to be installed and configured as quickly as possible, and perform this out of hours.
  • Educate users about the message, and what it really means – it’s warning of an outage, but it may not be an outage on their pool!
  • Consider limiting the number of users enabled for Persistent Chat – if only 10% of users need it, they’re the only ones who should be enabled. Others won’t see the “outage” warning if they’re not enabled for PChat in the first place.
  • Consider limiting the number of PChat pools in the organization. While you can collocate PChat on a Standard Edition server, this only makes sense in small environments. Don’t let the failure of a single server for 100 users cause an outage warning for 100,000+ users!

Hopefully some better logic around this warning will come in future versions of the Lync (or Skype for Business) client. In the meantime, think carefully about whether you want multiple PChat pools and if you do, what you need to do to avoid the dreaded “outage” message!

Persistent Chat – Server could not process your request

A quick and simple one from this week’s deployment of Lync Server 2013.

We got Persistent Chat up and running, created a category, and gave our test user rights to create rooms. Signed in to the Lync client, we selected “Create a Chat Room…”.


This launches a browser to:


..and we were hit with this error: Server could not process your request. Please try again later.


No errors in the Lync or Application event logs, and the only reference to the error I could find was this blog post at However, that problem relates to SBA-homed users, which definitely wasn’t the issue here.

The answer was in the IIS log for the Lync internal web site – by default, under C:\inetpub\Logs\W3SVC<siteID>\ (usually the lower siteID is the internal site). We saw the requests for /PersistentChat/RM?clientlang=en-US – but the username was that of the user who had logged in to Windows, not to Lync.

When we logged in to the PC as the test user, signed in to Lync and tried again, we got the chat room management page as expected and everything worked fine.