diff --git a/server/src/main/java/org/elasticsearch/index/mapper/TypeParsers.java b/server/src/main/java/org/elasticsearch/index/mapper/TypeParsers.java
index ac7025c5b323d..0b1ee2c7f4b71 100644
--- a/server/src/main/java/org/elasticsearch/index/mapper/TypeParsers.java
+++ b/server/src/main/java/org/elasticsearch/index/mapper/TypeParsers.java
@@ -354,7 +354,10 @@ private static IndexOptions nodeIndexOptionValue(final Object propNode) {
     }
 
     public static FormatDateTimeFormatter parseDateTimeFormatter(Object node) {
-        return Joda.forPattern(node.toString());
+        if (node instanceof String) {
+            return Joda.forPattern((String) node);
+        }
+        throw new IllegalArgumentException("Invalid format: [" + node.toString() + "]: expected string value");
     }
 
     public static void parseTermVector(String fieldName, String termVector, FieldMapper.Builder builder) throws MapperParsingException {
diff --git a/server/src/test/java/org/elasticsearch/index/mapper/DateFieldMapperTests.java b/server/src/test/java/org/elasticsearch/index/mapper/DateFieldMapperTests.java
index 97eb3454e90b1..a913a0f2ceb80 100644
--- a/server/src/test/java/org/elasticsearch/index/mapper/DateFieldMapperTests.java
+++ b/server/src/test/java/org/elasticsearch/index/mapper/DateFieldMapperTests.java
@@ -414,4 +414,22 @@ public void testMergeText() throws Exception {
                 () -> mapper.merge(update.mapping(), randomBoolean()));
         assertEquals("mapper [date] of different type, current_type [date], merged_type [text]", e.getMessage());
     }
+
+    public void testIllegalFormatField() throws Exception {
+        String mapping =  Strings.toString(XContentFactory.jsonBuilder()
+            .startObject()
+                .startObject("type")
+                    .startObject("properties")
+                        .startObject("field")
+                            .field("type", "date")
+                            .array("format", "test_format")
+                        .endObject()
+                    .endObject()
+                .endObject()
+            .endObject());
+
+        IllegalArgumentException e = expectThrows(IllegalArgumentException.class,
+                () -> parser.parse("type", new CompressedXContent(mapping)));
+        assertEquals("Invalid format: [[test_format]]: expected string value", e.getMessage());
+    }
 }
diff --git a/server/src/test/java/org/elasticsearch/index/mapper/RangeFieldMapperTests.java b/server/src/test/java/org/elasticsearch/index/mapper/RangeFieldMapperTests.java
index 54418850e5d4f..00068f76e753d 100644
--- a/server/src/test/java/org/elasticsearch/index/mapper/RangeFieldMapperTests.java
+++ b/server/src/test/java/org/elasticsearch/index/mapper/RangeFieldMapperTests.java
@@ -443,4 +443,22 @@ public void testSerializeDefaults() throws Exception {
         }
     }
 
+    public void testIllegalFormatField() throws Exception {
+        String mapping = Strings.toString(XContentFactory.jsonBuilder()
+            .startObject()
+                .startObject("type")
+                    .startObject("properties")
+                        .startObject("field")
+                            .field("type", "date_range")
+                            .array("format", "test_format")
+                        .endObject()
+                    .endObject()
+                .endObject()
+            .endObject());
+
+        IllegalArgumentException e = expectThrows(IllegalArgumentException.class,
+                () -> parser.parse("type", new CompressedXContent(mapping)));
+        assertEquals("Invalid format: [[test_format]]: expected string value", e.getMessage());
+    }
+
 }
diff --git a/server/src/test/java/org/elasticsearch/index/mapper/RootObjectMapperTests.java b/server/src/test/java/org/elasticsearch/index/mapper/RootObjectMapperTests.java
index e17fb9cc4b022..9be109c0b8420 100644
--- a/server/src/test/java/org/elasticsearch/index/mapper/RootObjectMapperTests.java
+++ b/server/src/test/java/org/elasticsearch/index/mapper/RootObjectMapperTests.java
@@ -159,4 +159,30 @@ public void testDynamicTemplates() throws Exception {
         mapper = mapperService.merge("type", new CompressedXContent(mapping3), MergeReason.MAPPING_UPDATE, false);
         assertEquals(mapping3, mapper.mappingSource().toString());
     }
+
+    public void testIllegalFormatField() throws Exception {
+        String dynamicMapping = Strings.toString(XContentFactory.jsonBuilder()
+            .startObject()
+                .startObject("type")
+                    .startArray("dynamic_date_formats")
+                        .startArray().value("test_format").endArray()
+                    .endArray()
+                .endObject()
+            .endObject());
+        String mapping = Strings.toString(XContentFactory.jsonBuilder()
+            .startObject()
+                .startObject("type")
+                    .startArray("date_formats")
+                        .startArray().value("test_format").endArray()
+                    .endArray()
+                .endObject()
+            .endObject());
+
+        DocumentMapperParser parser = createIndex("test").mapperService().documentMapperParser();
+        for (String m : Arrays.asList(mapping, dynamicMapping)) {
+            IllegalArgumentException e = expectThrows(IllegalArgumentException.class,
+                    () -> parser.parse("type", new CompressedXContent(m)));
+            assertEquals("Invalid format: [[test_format]]: expected string value", e.getMessage());
+        }
+    }
 }