In preparation for your Skype for Business InPlace Upgrade remember you need have update your SQL Express 2012 to at least SP1. You need to do this on all Lync servers so you may be busy if you have updated already. By default Lync 2013 installed only SQL 2012 Express with no SPs.

Heres the steps i did to update from RTM to SP2

1. First Check SQL DB Version (Test-CSDatabase is good for this)

2.Download sql 2012 sp2

http://www.microsoft.com/en-us/download/details.aspx?id=43340

3. Stop lync services (stop-csWindowsService)

4. Run sql 2012 update you downloaded

By default it selects all instances

5. Check Database version after install with Test-CsDatabase again.

Woohoo we have SP2!

6. Restart Lync Services