Mantis#1797. Thank you kindly, StrawberryFride for a patch that solves:

Shutdown command on region server was presenting an error, failing to 
send detach region for all regions, and failing to shut down

1 files changed, 1 insertions, 1 deletions

diff --git a/OpenSim/Region/Communications/OGS1/OGS1GridServices.cs b/OpenSim/Region/Communications/OGS1/OGS1GridServices.cs
index d8a6daf..a2cddec 100644
--- a/OpenSim/Region/Communications/OGS1/OGS1GridServices.cs
+++ b/OpenSim/Region/Communications/OGS1/OGS1GridServices.cs
@@ -206,7 +206,7 @@ namespace OpenSim.Region.Communications.OGS1
             // Hashtable griddatahash = GridRespData;
 
             // Process Response
-            if (GridRespData.ContainsKey("error"))
+            if (GridRespData != null && GridRespData.ContainsKey("error"))
             {
                 string errorstring = (string)GridRespData["error"];
                 m_log.Error("Unable to connect to grid: " + errorstring);