diff --git a/crmsh/constants.py b/crmsh/constants.py
index a89fbd334..3987ea285 100644
--- a/crmsh/constants.py
+++ b/crmsh/constants.py
@@ -517,4 +517,6 @@
 COROSYNC_STATUS_TYPES = ("ring", "quorum", "qdevice", "qnetd", "cpg")
 
 NO_SSH_ERROR_MSG = "ssh-related operations are disabled. crmsh works in local mode."
+
+SANITY_FATAL_RC = 100
 # vim:ts=4:sw=4:et:
diff --git a/crmsh/ra.py b/crmsh/ra.py
index 211caabb0..fc202f4dd 100644
--- a/crmsh/ra.py
+++ b/crmsh/ra.py
@@ -640,8 +640,8 @@ def sanity_check_op(op, op_dict):
             if self.ra_class == "stonith" and op in ("start", "stop"):
                 return rc
             if op not in self.actions():
-                logger.warning("%s: action '%s' not found in Resource Agent meta-data", ident, op)
-                rc |= 1
+                logger.error("Action '%s' not found in Resource Agent meta-data", op)
+                rc |= constants.SANITY_FATAL_RC
                 return rc
             rc |= sanity_check_op_interval(op, op_dict)
             rc |= sanity_check_op_timeout(op, op_dict)
diff --git a/crmsh/ui_configure.py b/crmsh/ui_configure.py
index 4a868591f..85de94ce9 100644
--- a/crmsh/ui_configure.py
+++ b/crmsh/ui_configure.py
@@ -755,6 +755,8 @@ def _verify(self, set_obj_semantic, set_obj_all):
         rc1 = set_obj_all.verify()
         if config.core.check_frequency != "never":
             rc2 = set_obj_semantic.semantic_check(set_obj_all)
+            if rc2 >= constants.SANITY_FATAL_RC:
+                raise utils.TerminateSubCommand
         else:
             rc2 = 0
         return rc1 and rc2 <= 1
@@ -934,7 +936,10 @@ def _commit(self, force=False, replace=False):
         rc1 = True
         if replace and not force:
             rc1 = cib_factory.is_current_cib_equal()
-        rc2 = self._verify(mkset_obj("xml", "changed"), mkset_obj("xml"))
+        try:
+            rc2 = self._verify(mkset_obj("xml", "changed"), mkset_obj("xml"))
+        except utils.TerminateSubCommand:
+            return False
         if rc1 and rc2:
             return cib_factory.commit(replace=replace)
         if force or config.core.force:
diff --git a/crmsh/utils.py b/crmsh/utils.py
index ac77669e5..f94564f98 100644
--- a/crmsh/utils.py
+++ b/crmsh/utils.py
@@ -288,7 +288,7 @@ def ask(msg, background_wait=True, cancel_option=False):
     if not can_ask(background_wait):
         return False
 
-    option_str = "y/n" + "/c" if cancel_option else ""
+    option_str = "y/n" + ("/c" if cancel_option else "")
     msg += ' '
     if msg.endswith('? '):
         msg = msg[:-2] + f'  ({option_str})? '
diff --git a/test/features/resource_set.feature b/test/features/resource_set.feature
index f2f5f3815..b951d4582 100644
--- a/test/features/resource_set.feature
+++ b/test/features/resource_set.feature
@@ -185,3 +185,10 @@ Feature: Use "crm configure set" to update attributes and operations
     And     Run "crm configure load xml update /tmp/d.xml" on "hanode1"
     And     Try "crm configure show|grep -E "^xml <primitive""
     Then    Expected return code is "1"
+
+  @clean
+  Scenario: Prevent adding unknown operation (bsc#1236442)
+    When    Try "crm configure primitive stateful-1 ocf:pacemaker:Stateful op monitor_Slave interval=10s op monitor_Master interval=5s" on "hanode1"
+    Then    Expected "not found in Resource Agent meta-data" in stderr
+    When    Try "crm configure show stateful-1" on "hanode1"
+    Then    Expected "object stateful-1 does not exist" in stderr