--- a/pkg/imports/agm.go	Wed May 08 11:45:57 2019 +0200
+++ b/pkg/imports/agm.go	Wed May 08 12:45:21 2019 +0200
@@ -326,11 +326,14 @@
 	checkedGauges := map[models.Isrs]bool{}
 
 lines:
-	for line := 1; ; line++ {
+	for line, ignored := 1, 0; ; line++ {
 
 		row, err := r.Read()
 		switch {
 		case err == io.EOF || len(row) == 0:
+			if ignored == line-1 {
+				return nil, UnchangedError("No entries imported")
+			}
 			break lines
 		case err != nil:
 			return nil, fmt.Errorf("CSV parsing failed: %v", err)
@@ -345,6 +348,7 @@
 		if exists, found := checkedGauges[*gid]; found {
 			if !exists {
 				// Just ignore the line since we have already warned
+				ignored++
 				continue lines
 			}
 		} else { // not found in gauge cache
@@ -361,6 +365,7 @@
 			checkedGauges[*gid] = exists
 			if !exists {
 				feedback.Warn("Ignoring data for unknown gauge %s", gid.String())
+				ignored++
 				continue lines
 			}
 		}