diff --git a/casadm/cas_lib.c b/casadm/cas_lib.c
index c0b53f1..9066d71 100644
--- a/casadm/cas_lib.c
+++ b/casadm/cas_lib.c
@@ -3033,9 +3033,17 @@ int standby_activate(int cache_id, const char *cache_device)
 	}
 
 	if (cas_ioctl(KCAS_IOCTL_STANDBY_ACTIVATE, &cmd) != SUCCESS) {
-		print_err(cmd.ext_err_code ? : KCAS_ERR_SYSTEM);
+		if (abs(cmd.ext_err_code) == OCF_ERR_NOT_OPEN_EXC) {
+			cas_printf(LOG_ERR, "Cannot open the device exclusively. Make sure "
+					"to detach cache before activation.\n");
+		} else {
+			print_err(cmd.ext_err_code ? : KCAS_ERR_SYSTEM);
+		}
 		return FAILURE;
 	}
 
+	cas_printf(LOG_INFO, "Successfully activated cache instance %hu\n",
+			cache_id);
+
 	return SUCCESS;
 }