diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 1ca9049fc8..4715252e39 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -16,6 +16,10 @@ Fixed
 
   Contributed by @momokuri-3
 
+* Fix exception thrown if action parameter contains {{ or {% and no closing jinja characters. #5556
+
+  contributed by @guzzijones12
+
 Added
 ~~~~~
 
diff --git a/st2common/st2common/util/param.py b/st2common/st2common/util/param.py
index 52e1f025fd..90617a78d9 100644
--- a/st2common/st2common/util/param.py
+++ b/st2common/st2common/util/param.py
@@ -19,7 +19,7 @@
 import six
 import networkx as nx
 
-from jinja2 import meta
+from jinja2 import meta, exceptions
 from oslo_config import cfg
 from st2common import log as logging
 from st2common.util.config_loader import get_config
@@ -133,19 +133,24 @@ def _process(G, name, value):
     ) or jinja_utils.is_jinja_expression(complex_value_str)
 
     if is_jinja_expr:
-        G.add_node(name, template=value)
-
-        template_ast = ENV.parse(value)
-        LOG.debug("Template ast: %s", template_ast)
-        # Dependencies of the node represent jinja variables used in the template
-        # We're connecting nodes with an edge for every depencency to traverse them
-        # in the right order and also make sure that we don't have missing or cyclic
-        # dependencies upfront.
-        dependencies = meta.find_undeclared_variables(template_ast)
-        LOG.debug("Dependencies: %s", dependencies)
-        if dependencies:
-            for dependency in dependencies:
-                G.add_edge(dependency, name)
+        try:
+            template_ast = ENV.parse(value)
+            G.add_node(name, template=value)
+
+            LOG.debug("Template ast: %s", template_ast)
+            # Dependencies of the node represent jinja variables used in the template
+            # We're connecting nodes with an edge for every depencency to traverse them
+            # in the right order and also make sure that we don't have missing or cyclic
+            # dependencies upfront.
+            dependencies = meta.find_undeclared_variables(template_ast)
+            LOG.debug("Dependencies: %s", dependencies)
+            if dependencies:
+                for dependency in dependencies:
+                    G.add_edge(dependency, name)
+        except exceptions.TemplateSyntaxError:
+            G.add_node(name, value=value)
+            # not jinja after all
+            # is_jinga_expression only checks for {{ or {{% for speed
     else:
         G.add_node(name, value=value)
 
diff --git a/st2common/tests/unit/test_param_utils.py b/st2common/tests/unit/test_param_utils.py
index c2e5810815..77c88b1cd3 100644
--- a/st2common/tests/unit/test_param_utils.py
+++ b/st2common/tests/unit/test_param_utils.py
@@ -54,6 +54,26 @@ class ParamsUtilsTest(DbTestCase):
     action_system_default_db = FIXTURES["actions"]["action_system_default.yaml"]
     runnertype_db = FIXTURES["runners"]["testrunner1.yaml"]
 
+    def test_process_jinja_exception(self):
+
+        action_context = {"api_user": "noob"}
+        config = {}
+        G = param_utils._create_graph(action_context, config)
+        name = "a1"
+        value = {"test": "http://someurl?value={{a"}
+        param_utils._process(G, name, value)
+        self.assertEquals(G.nodes.get(name, {}).get("value"), value)
+
+    def test_process_jinja_template(self):
+
+        action_context = {"api_user": "noob"}
+        config = {}
+        G = param_utils._create_graph(action_context, config)
+        name = "a1"
+        value = "http://someurl?value={{a}}"
+        param_utils._process(G, name, value)
+        self.assertEquals(G.nodes.get(name, {}).get("template"), value)
+
     def test_get_finalized_params(self):
         params = {
             "actionstr": "foo",