Check for the submodule

QGCExternalLibs.pri

@@ -107,20 +107,25 @@ else {
 
 # Then we add the proper include paths dependent on the dialect.
 INCLUDEPATH += $$MAVLINKPATH
-!isEmpty(MAVLINK_CONF) {
-    count(MAVLINK_CONF, 1) {
-        exists($$MAVLINKPATH/$$MAVLINK_CONF) {
-            INCLUDEPATH += $$MAVLINKPATH/$$MAVLINK_CONF
-            DEFINES += $$sprintf('QGC_USE_%1_MESSAGES', $$upper($$MAVLINK_CONF))
+
+exists($$MAVLINKPATH/common) {
+    !isEmpty(MAVLINK_CONF) {
+        count(MAVLINK_CONF, 1) {
+            exists($$MAVLINKPATH/$$MAVLINK_CONF) {
+                INCLUDEPATH += $$MAVLINKPATH/$$MAVLINK_CONF
+                DEFINES += $$sprintf('QGC_USE_%1_MESSAGES', $$upper($$MAVLINK_CONF))
+            } else {
+                error($$sprintf("MAVLink dialect '%1' does not exist at '%2'!", $$MAVLINK_CONF, $$MAVLINKPATH_REL))
+            }
         } else {
-            error($$sprintf("MAVLink dialect '%1' does not exist at '%2'!", $$MAVLINK_CONF, $$MAVLINKPATH_REL))
+            error(Only a single mavlink dialect can be specified in MAVLINK_CONF)
         }
     } else {
-        error(Only a single mavlink dialect can be specified in MAVLINK_CONF)
+        warning("No MAVLink dialect specified, only common messages supported.")
+        INCLUDEPATH += $$MAVLINKPATH/common
     }
 } else {
-    warning("No MAVLink dialect specified, only common messages supported.")
-    INCLUDEPATH += $$MAVLINKPATH/common
+    error($$sprintf("MAVLink folder does not exist at '%1'! Run 'git submodule init && git submodule update' on the command line.",$$MAVLINKPATH_REL))
 }
 
 #