diff --git a/src/IO.f90 b/src/IO.f90
index 0542e7a62..ee35cf1bc 100644
--- a/src/IO.f90
+++ b/src/IO.f90
@@ -498,6 +498,9 @@ subroutine IO_error(error_ID,el,ip,g,instance,ext_msg)
       msg = 'Abrupt end of file'
     case (708)
       msg = '--- expected after YAML file header'
+    case (710)
+      msg = 'key mismatch'
+
 
 !-------------------------------------------------------------------------------------------------
 ! errors related to the grid solver
diff --git a/src/YAML_types.f90 b/src/YAML_types.f90
index cc1c85efd..86acf05be 100644
--- a/src/YAML_types.f90
+++ b/src/YAML_types.f90
@@ -952,6 +952,9 @@ function tNode_get_byKey_asIndex(self,key)  result(keyIndex)
     endif
   enddo
 
+  if(keyIndex == -1) call IO_error(710,ext_msg=key)
+
+ 
 end function tNode_get_byKey_asIndex