KnowledgeBase/CII.md

@@ -1727,4 +1727,25 @@ namespace da {
 
 A test application showing its use is here:
 
-<https://gitlab.eso.org/cosylab/elt-cii/mal/mal-test/-/blob/develop/cpp/mal-test-performance/opcua/mal-opcua-da-speed/src/common.cpp>
+<https://gitlab.eso.org/cosylab/elt-cii/mal/mal-test/-/blob/develop/cpp/mal-test-performance/opcua/mal-opcua-da-speed/src/common.cpp>
\ No newline at end of file
+
+
+
+--------------------------------------------------------------------------
+--------------------------------------------------------------------------
+--------------------------------------------------------------------------
+### Exception connecting to config service
+
+When starting an application using the Config client API and the following exception is received:
+```
+<date/time>, ERROR, CiiOldbFactory/140635105143296, Unexpected config exception occurred while retrieving configuration for cii.config://remote/oldb/configurations/oldbClientConfig What:Path oldb/configurations/oldbClientConfig, version -1 not found
+terminate called after throwing an instance of 'elt::oldb::CiiOldbException'
+what(): Unexpected config exception occurred while retrieving configuration for cii.config://remote/oldb/configurations/oldbClientConfig What:Path oldb/configurations/oldbClientConfig, version -1 not found
+```
+
+*info*
+This can indicate that elasticSearch on the config/oldb server is not running, or has crashed.
+Use cii-services command to check the status on the server where the config is running.
+
+
+