diff --git a/buildSrc/src/main/resources/checkstyle_suppressions.xml b/buildSrc/src/main/resources/checkstyle_suppressions.xml
index ffad8d37c5b..27b9efbf0a4 100644
--- a/buildSrc/src/main/resources/checkstyle_suppressions.xml
+++ b/buildSrc/src/main/resources/checkstyle_suppressions.xml
@@ -712,7 +712,6 @@
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]action[/\\]admin[/\\]cluster[/\\]stats[/\\]ClusterStatsIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]action[/\\]admin[/\\]indices[/\\]TransportAnalyzeActionTests.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]action[/\\]admin[/\\]indices[/\\]cache[/\\]clear[/\\]ClearIndicesCacheBlocksIT.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]action[/\\]admin[/\\]indices[/\\]create[/\\]CreateIndexIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]action[/\\]admin[/\\]indices[/\\]flush[/\\]SyncedFlushUnitTests.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]action[/\\]admin[/\\]indices[/\\]get[/\\]GetIndexIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]action[/\\]admin[/\\]indices[/\\]shards[/\\]IndicesShardStoreRequestIT.java" checks="LineLength" />
@@ -1022,7 +1021,6 @@
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]indices[/\\]state[/\\]CloseIndexDisableCloseAllIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]indices[/\\]state[/\\]OpenCloseIndexIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]indices[/\\]state[/\\]RareClusterStateIT.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]indices[/\\]state[/\\]SimpleIndexStateIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]indices[/\\]stats[/\\]IndexStatsIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]indices[/\\]store[/\\]IndicesStoreIntegrationIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]indices[/\\]store[/\\]IndicesStoreTests.java" checks="LineLength" />
diff --git a/core/src/main/java/org/elasticsearch/common/settings/AbstractScopedSettings.java b/core/src/main/java/org/elasticsearch/common/settings/AbstractScopedSettings.java
index 0170c4218a2..817e109bf4d 100644
--- a/core/src/main/java/org/elasticsearch/common/settings/AbstractScopedSettings.java
+++ b/core/src/main/java/org/elasticsearch/common/settings/AbstractScopedSettings.java
@@ -263,6 +263,9 @@ public abstract class AbstractScopedSettings extends AbstractComponent {
             List<String> keys = scoredKeys.stream().map((a) -> a.v2()).collect(Collectors.toList());
             if (keys.isEmpty() == false) {
                 msg += " did you mean " + (keys.size() == 1 ? "[" + keys.get(0) + "]": "any of " + keys.toString()) + "?";
+            } else {
+                msg += " please check that any required plugins are installed, or check the breaking changes documentation for removed " +
+                    "settings";
             }
             throw new IllegalArgumentException(msg);
         }
diff --git a/core/src/test/java/org/elasticsearch/action/admin/indices/create/CreateIndexIT.java b/core/src/test/java/org/elasticsearch/action/admin/indices/create/CreateIndexIT.java
index 8fbb489d9c2..3e7323dceeb 100644
--- a/core/src/test/java/org/elasticsearch/action/admin/indices/create/CreateIndexIT.java
+++ b/core/src/test/java/org/elasticsearch/action/admin/indices/create/CreateIndexIT.java
@@ -70,7 +70,8 @@ public class CreateIndexIT extends ESIntegTestCase {
             prepareCreate("test").setSettings(Settings.builder().put(IndexMetaData.SETTING_CREATION_DATE, 4L)).get();
             fail();
         } catch (IllegalArgumentException ex) {
-            assertEquals("unknown setting [index.creation_date]", ex.getMessage());
+            assertEquals("unknown setting [index.creation_date] please check that any required plugins are installed, or check the " +
+                "breaking changes documentation for removed settings", ex.getMessage());
         }
     }
 
@@ -165,7 +166,8 @@ public class CreateIndexIT extends ESIntegTestCase {
                 .get();
             fail("should have thrown an exception about the shard count");
         } catch (IllegalArgumentException e) {
-            assertEquals("unknown setting [index.unknown.value]", e.getMessage());
+            assertEquals("unknown setting [index.unknown.value] please check that any required plugins are installed, or check the" +
+                " breaking changes documentation for removed settings", e.getMessage());
         }
     }
 
@@ -211,13 +213,16 @@ public class CreateIndexIT extends ESIntegTestCase {
                      @Override
                     public void run() {
                          try {
-                             client().prepareIndex("test", "test").setSource("index_version", indexVersion.get()).get(); // recreate that index
+                             // recreate that index
+                             client().prepareIndex("test", "test").setSource("index_version", indexVersion.get()).get();
                              synchronized (indexVersionLock) {
-                                 // we sync here since we have to ensure that all indexing operations below for a given ID are done before we increment the
-                                 // index version otherwise a doc that is in-flight could make it into an index that it was supposed to be deleted for and our assertion fail...
+                                 // we sync here since we have to ensure that all indexing operations below for a given ID are done before
+                                 // we increment the index version otherwise a doc that is in-flight could make it into an index that it
+                                 // was supposed to be deleted for and our assertion fail...
                                  indexVersion.incrementAndGet();
                              }
-                             assertAcked(client().admin().indices().prepareDelete("test").get()); // from here on all docs with index_version == 0|1 must be gone!!!! only 2 are ok;
+                             // from here on all docs with index_version == 0|1 must be gone!!!! only 2 are ok;
+                             assertAcked(client().admin().indices().prepareDelete("test").get());
                          } finally {
                              latch.countDown();
                          }
@@ -249,8 +254,10 @@ public class CreateIndexIT extends ESIntegTestCase {
         latch.await();
         refresh();
 
-        // we only really assert that we never reuse segments of old indices or anything like this here and that nothing fails with crazy exceptions
-        SearchResponse expected = client().prepareSearch("test").setIndicesOptions(IndicesOptions.lenientExpandOpen()).setQuery(new RangeQueryBuilder("index_version").from(indexVersion.get(), true)).get();
+        // we only really assert that we never reuse segments of old indices or anything like this here and that nothing fails with
+        // crazy exceptions
+        SearchResponse expected = client().prepareSearch("test").setIndicesOptions(IndicesOptions.lenientExpandOpen())
+            .setQuery(new RangeQueryBuilder("index_version").from(indexVersion.get(), true)).get();
         SearchResponse all = client().prepareSearch("test").setIndicesOptions(IndicesOptions.lenientExpandOpen()).get();
         assertEquals(expected + " vs. " + all, expected.getHits().getTotalHits(), all.getHits().getTotalHits());
         logger.info("total: {}", expected.getHits().getTotalHits());
@@ -283,7 +290,8 @@ public class CreateIndexIT extends ESIntegTestCase {
     }
 
     public void testRestartIndexCreationAfterFullClusterRestart() throws Exception {
-        client().admin().cluster().prepareUpdateSettings().setTransientSettings(Settings.builder().put("cluster.routing.allocation.enable", "none")).get();
+        client().admin().cluster().prepareUpdateSettings().setTransientSettings(Settings.builder().put("cluster.routing.allocation.enable",
+            "none")).get();
         client().admin().indices().prepareCreate("test").setSettings(indexSettings()).get();
         internalCluster().fullRestart();
         ensureGreen("test");
diff --git a/core/src/test/java/org/elasticsearch/common/settings/ScopedSettingsTests.java b/core/src/test/java/org/elasticsearch/common/settings/ScopedSettingsTests.java
index 3afd60d86e4..664f8cb96ab 100644
--- a/core/src/test/java/org/elasticsearch/common/settings/ScopedSettingsTests.java
+++ b/core/src/test/java/org/elasticsearch/common/settings/ScopedSettingsTests.java
@@ -202,20 +202,22 @@ public class ScopedSettingsTests extends ESTestCase {
         IndexScopedSettings settings = new IndexScopedSettings(
             Settings.EMPTY,
             IndexScopedSettings.BUILT_IN_INDEX_SETTINGS);
+        String unknownMsgSuffix = " please check that any required plugins are installed, or check the breaking changes documentation for" +
+            " removed settings";
         settings.validate(Settings.builder().put("index.store.type", "boom"));
         settings.validate(Settings.builder().put("index.store.type", "boom").build());
         try {
             settings.validate(Settings.builder().put("index.store.type", "boom", "i.am.not.a.setting", true));
             fail();
         } catch (IllegalArgumentException e) {
-            assertEquals("unknown setting [i.am.not.a.setting]", e.getMessage());
+            assertEquals("unknown setting [i.am.not.a.setting]" + unknownMsgSuffix, e.getMessage());
         }
 
         try {
             settings.validate(Settings.builder().put("index.store.type", "boom", "i.am.not.a.setting", true).build());
             fail();
         } catch (IllegalArgumentException e) {
-            assertEquals("unknown setting [i.am.not.a.setting]", e.getMessage());
+            assertEquals("unknown setting [i.am.not.a.setting]" + unknownMsgSuffix, e.getMessage());
         }
 
         try {
diff --git a/core/src/test/java/org/elasticsearch/common/settings/SettingsModuleTests.java b/core/src/test/java/org/elasticsearch/common/settings/SettingsModuleTests.java
index 353b7b61d6c..692134916ef 100644
--- a/core/src/test/java/org/elasticsearch/common/settings/SettingsModuleTests.java
+++ b/core/src/test/java/org/elasticsearch/common/settings/SettingsModuleTests.java
@@ -51,7 +51,8 @@ public class SettingsModuleTests extends ModuleTestCase {
                 () -> new SettingsModule(settings));
             assertEquals("Failed to parse value [[2.0]] for setting [cluster.routing.allocation.balance.shard]", ex.getMessage());
             assertEquals(1, ex.getSuppressed().length);
-            assertEquals("unknown setting [some.foo.bar]", ex.getSuppressed()[0].getMessage());
+            assertEquals("unknown setting [some.foo.bar] please check that any required plugins are installed, or check the breaking " +
+                "changes documentation for removed settings", ex.getSuppressed()[0].getMessage());
         }
 
         {
@@ -127,7 +128,8 @@ public class SettingsModuleTests extends ModuleTestCase {
                 new SettingsModule(settings);
                 fail();
             } catch (IllegalArgumentException ex) {
-                assertEquals("tribe.blocks validation failed: unknown setting [wtf]", ex.getMessage());
+                assertEquals("tribe.blocks validation failed: unknown setting [wtf] please check that any required plugins are" +
+                    " installed, or check the breaking changes documentation for removed settings", ex.getMessage());
             }
         }
     }
diff --git a/core/src/test/java/org/elasticsearch/indices/state/SimpleIndexStateIT.java b/core/src/test/java/org/elasticsearch/indices/state/SimpleIndexStateIT.java
index f3898bc9f3c..ea3ebf5179b 100644
--- a/core/src/test/java/org/elasticsearch/indices/state/SimpleIndexStateIT.java
+++ b/core/src/test/java/org/elasticsearch/indices/state/SimpleIndexStateIT.java
@@ -56,7 +56,8 @@ public class SimpleIndexStateIT extends ESIntegTestCase {
         ClusterStateResponse stateResponse = client().admin().cluster().prepareState().get();
         assertThat(stateResponse.getState().metaData().index("test").getState(), equalTo(IndexMetaData.State.OPEN));
         assertThat(stateResponse.getState().routingTable().index("test").shards().size(), equalTo(numShards.numPrimaries));
-        assertThat(stateResponse.getState().routingTable().index("test").shardsWithState(ShardRoutingState.STARTED).size(), equalTo(numShards.totalNumShards));
+        assertEquals(stateResponse.getState().routingTable().index("test").shardsWithState(ShardRoutingState.STARTED).size()
+            , numShards.totalNumShards);
 
         logger.info("--> indexing a simple document");
         client().prepareIndex("test", "type1", "1").setSource("field1", "value1").get();
@@ -88,7 +89,8 @@ public class SimpleIndexStateIT extends ESIntegTestCase {
         assertThat(stateResponse.getState().metaData().index("test").getState(), equalTo(IndexMetaData.State.OPEN));
 
         assertThat(stateResponse.getState().routingTable().index("test").shards().size(), equalTo(numShards.numPrimaries));
-        assertThat(stateResponse.getState().routingTable().index("test").shardsWithState(ShardRoutingState.STARTED).size(), equalTo(numShards.totalNumShards));
+        assertEquals(stateResponse.getState().routingTable().index("test").shardsWithState(ShardRoutingState.STARTED).size(),
+            numShards.totalNumShards);
 
         logger.info("--> indexing a simple document");
         client().prepareIndex("test", "type1", "1").setSource("field1", "value1").get();
@@ -119,7 +121,8 @@ public class SimpleIndexStateIT extends ESIntegTestCase {
         ClusterStateResponse stateResponse = client().admin().cluster().prepareState().get();
         assertThat(stateResponse.getState().metaData().index("test").getState(), equalTo(IndexMetaData.State.OPEN));
         assertThat(stateResponse.getState().routingTable().index("test").shards().size(), equalTo(numShards.numPrimaries));
-        assertThat(stateResponse.getState().routingTable().index("test").shardsWithState(ShardRoutingState.STARTED).size(), equalTo(numShards.totalNumShards));
+        assertEquals(stateResponse.getState().routingTable().index("test").shardsWithState(ShardRoutingState.STARTED).size(),
+            numShards.totalNumShards);
 
         logger.info("--> indexing a simple document");
         client().prepareIndex("test", "type1", "1").setSource("field1", "value1").get();
@@ -143,7 +146,8 @@ public class SimpleIndexStateIT extends ESIntegTestCase {
         }
 
         logger.info("--> creating test index with valid settings ");
-        CreateIndexResponse response = client().admin().indices().prepareCreate("test").setSettings(Settings.builder().put("number_of_shards", 1)).get();
+        CreateIndexResponse response = client().admin().indices().prepareCreate("test")
+            .setSettings(Settings.builder().put("number_of_shards", 1)).get();
         assertThat(response.isAcknowledged(), equalTo(true));
     }
 }
diff --git a/core/src/test/java/org/elasticsearch/indices/template/SimpleIndexTemplateIT.java b/core/src/test/java/org/elasticsearch/indices/template/SimpleIndexTemplateIT.java
index 298cb9cd9e3..493f8b74e04 100644
--- a/core/src/test/java/org/elasticsearch/indices/template/SimpleIndexTemplateIT.java
+++ b/core/src/test/java/org/elasticsearch/indices/template/SimpleIndexTemplateIT.java
@@ -322,7 +322,8 @@ public class SimpleIndexTemplateIT extends ESIntegTestCase {
                 .setTemplate("te*")
                 .setSettings(Settings.builder().put("does_not_exist", "test"))
                 .get());
-        assertEquals("unknown setting [index.does_not_exist]", e.getMessage());
+        assertEquals("unknown setting [index.does_not_exist] please check that any required plugins are" +
+            " installed, or check the breaking changes documentation for removed settings", e.getMessage());
 
         response = client().admin().indices().prepareGetTemplates().get();
         assertEquals(0, response.getIndexTemplates().size());