diff --git a/graylog2-server/src/main/java/org/graylog2/plugin/Message.java b/graylog2-server/src/main/java/org/graylog2/plugin/Message.java
index 9a12cc6426aa5..60bab2e01b8c1 100644
--- a/graylog2-server/src/main/java/org/graylog2/plugin/Message.java
+++ b/graylog2-server/src/main/java/org/graylog2/plugin/Message.java
@@ -19,6 +19,7 @@
 import com.codahale.metrics.Meter;
 import com.eaio.uuid.UUID;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.github.joschi.jadconfig.Parameter;
 import com.google.common.base.Function;
 import com.google.common.base.Joiner;
 import com.google.common.base.Objects;
@@ -299,6 +300,9 @@ public class Message implements Messages, Indexable {
 
     private static final IdentityHashMap<Class<?>, Integer> classSizes = Maps.newIdentityHashMap();
 
+    @Parameter(value = "replace_dots_in_field_names")
+    private boolean replaceDotsInFieldNames = true;
+
     static {
         classSizes.put(byte.class, 1);
         classSizes.put(Byte.class, 1);
@@ -402,9 +406,10 @@ public Map<String, Object> toElasticSearchObject(ObjectMapper objectMapper, @Non
             }
 
             final Object value = entry.getValue();
-            // Elasticsearch does not allow "." characters in keys since version 2.0.
+            // Elasticsearch does not allow "." characters in keys from versions 2.0 to 5.0 (excluded).
             // See: https://www.elastic.co/guide/en/elasticsearch/reference/2.0/breaking_20_mapping_changes.html#_field_names_may_not_contain_dots
-            if (key.contains(".")) {
+            // See: https://www.elastic.co/guide/en/elasticsearch/reference/5.0/release-notes-5.0.0.html#enhancement-5.0.0
+            if (key.contains(".") && replaceDotsInFieldNames) {
                 final String newKey = key.replace('.', KEY_REPLACEMENT_CHAR);
 
                 // If the message already contains the transformed key, we skip the field and emit a warning.
diff --git a/graylog2-web-interface/src/components/extractors/extractors_configuration/JSONExtractorConfiguration.jsx b/graylog2-web-interface/src/components/extractors/extractors_configuration/JSONExtractorConfiguration.jsx
index 85299adda73ca..403e3e72f7be2 100644
--- a/graylog2-web-interface/src/components/extractors/extractors_configuration/JSONExtractorConfiguration.jsx
+++ b/graylog2-web-interface/src/components/extractors/extractors_configuration/JSONExtractorConfiguration.jsx
@@ -100,6 +100,13 @@ const JSONExtractorConfiguration = createReactClass({
     return this.state.trying || !this.props.exampleMessage;
   },
 
+  _keySeparatorError(separator) {
+    if (separator.includes("."))
+      return "Warning: Elasticsearch does not allow '.' in field names from version 2.0 up to 5.0 (excluded)"
+    else
+      return null
+  },
+
   render() {
     return (
       <div>
@@ -129,6 +136,7 @@ const JSONExtractorConfiguration = createReactClass({
                defaultValue={this.state.configuration.key_separator}
                required
                onChange={this._onChange('key_separator')}
+               error={this._keySeparatorError(this.state.configuration.key_separator)}
                help={<span>What string to use to concatenate different keys of a nested JSON object (only used if <em>not</em> flattened).</span>} />
 
         <Input type="text"
diff --git a/misc/graylog.conf b/misc/graylog.conf
index 2a2aa7c45bf79..259e4c3019e6f 100644
--- a/misc/graylog.conf
+++ b/misc/graylog.conf
@@ -406,6 +406,13 @@ allow_leading_wildcard_searches = false
 # should only be enabled after making sure your Elasticsearch cluster has enough memory.
 allow_highlighting = false
 
+# Replace "." characters in keys with "_". Dots are not allowed by Elasticsearch version 2.0 up to 5.0 (excluded).
+# Support have been restored in Elasticsearch 5.0.
+# See: https://www.elastic.co/guide/en/elasticsearch/reference/2.0/breaking_20_mapping_changes.html#_field_names_may_not_contain_dots
+# See: https://www.elastic.co/guide/en/elasticsearch/reference/5.0/release-notes-5.0.0.html#enhancement-5.0.0
+# Default: true
+#replace_dots_in_field_names = true
+
 # Global timeout for index optimization (force merge) requests.
 # Default: 1h
 #elasticsearch_index_optimization_timeout = 1h