diff --git a/mxcubeweb/core/components/samplechanger.py b/mxcubeweb/core/components/samplechanger.py
index a86aaf64..a0756ab5 100644
--- a/mxcubeweb/core/components/samplechanger.py
+++ b/mxcubeweb/core/components/samplechanger.py
@@ -283,6 +283,13 @@ def unmount_sample_clean_up(self, sample):
 
     def mount_sample(self, sample):
         gevent.spawn(self.mount_sample_clean_up, sample)
+        sc = HWR.beamline.sample_changer
+
+        if not sc.is_ready():
+            raise Exception("Sample changer is busy, the sample can not be loaded.")
+        else:
+            gevent.spawn(self.mount_sample_clean_up, sample)
+
         return self.get_sc_contents()
 
     def unmount_sample(self, sample):