diff --git a/solr/CHANGES.txt b/solr/CHANGES.txt
index 26ea96a2544..663ec6c8d43 100644
--- a/solr/CHANGES.txt
+++ b/solr/CHANGES.txt
@@ -194,6 +194,8 @@ Bug Fixes
 
 * SOLR-16808: Stop publishing environment variables via the Metrics API (Houston Putman)
 
+* SOLR-16811: /update/json/docs?echo and mapUniqueKeyOnly params doesn't work (Mikhail Khludnev)
+
 Dependency Upgrades
 ---------------------
 * PR#1494: Upgrade forbiddenapis to 3.5 (Uwe Schindler)
diff --git a/solr/core/src/java/org/apache/solr/handler/loader/JsonLoader.java b/solr/core/src/java/org/apache/solr/handler/loader/JsonLoader.java
index 868b88ddc30..82231d098cb 100644
--- a/solr/core/src/java/org/apache/solr/handler/loader/JsonLoader.java
+++ b/solr/core/src/java/org/apache/solr/handler/loader/JsonLoader.java
@@ -295,10 +295,9 @@ public void handle(Map<String, Object> record, String path) {
 
     private Map<String, Object> getDocMap(
         Map<String, Object> record, JSONParser parser, String srcField, boolean mapUniqueKeyOnly) {
-      Map<String, Object> result = record;
+      Map<String, Object> result = mapUniqueKeyOnly ? record : new LinkedHashMap<>(record);
       if (srcField != null && parser instanceof RecordingJSONParser) {
         // if srcFIeld specified extract it out first
-        result = new LinkedHashMap<>(record);
         RecordingJSONParser rjp = (RecordingJSONParser) parser;
         result.put(srcField, rjp.getBuf());
         rjp.resetBuf();
@@ -320,7 +319,9 @@ private Map<String, Object> getDocMap(
         if (srcField != null && result.containsKey(srcField)) {
           copy.put(srcField, result.remove(srcField));
         }
-        copy.put(df, result.values());
+        final List<Object> deepValues = new ArrayList<>();
+        deepValues.addAll(result.values());
+        copy.put(df, deepValues);
         result = copy;
       }
 
diff --git a/solr/core/src/test/org/apache/solr/handler/JsonLoaderTest.java b/solr/core/src/test/org/apache/solr/handler/JsonLoaderTest.java
index e43bc486cec..f0be036bf9d 100644
--- a/solr/core/src/test/org/apache/solr/handler/JsonLoaderTest.java
+++ b/solr/core/src/test/org/apache/solr/handler/JsonLoaderTest.java
@@ -16,6 +16,8 @@
  */
 package org.apache.solr.handler;
 
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
 import java.util.function.UnaryOperator;
@@ -23,6 +25,7 @@
 import org.apache.solr.common.SolrException;
 import org.apache.solr.common.SolrInputDocument;
 import org.apache.solr.common.SolrInputField;
+import org.apache.solr.common.params.ModifiableSolrParams;
 import org.apache.solr.common.util.ContentStreamBase;
 import org.apache.solr.common.util.Utils;
 import org.apache.solr.handler.loader.JsonLoader;
@@ -300,25 +303,6 @@ public void testJsonDocFormat() throws Exception {
     assertEquals("v2", obj.get("f2"));
     assertTrue(obj.containsKey("f3"));
 
-    // TODO new test method
-    doc = "[{'id':'1'},{'id':'2'}]".replace('\'', '"');
-    req = req("srcField", "_src_");
-    req.getContext().put("path", "/update/json/docs");
-    rsp = new SolrQueryResponse();
-    p = new BufferingRequestProcessor(null);
-    loader = new JsonLoader();
-    loader.load(req, rsp, new ContentStreamBase.StringStream(doc), p);
-    assertEquals(2, p.addCommands.size());
-
-    content = (String) p.addCommands.get(0).solrDoc.getFieldValue("_src_");
-    assertNotNull(content);
-    obj = (Map) Utils.fromJSONString(content);
-    assertEquals("1", obj.get("id"));
-    content = (String) p.addCommands.get(1).solrDoc.getFieldValue("_src_");
-    assertNotNull(content);
-    obj = (Map) Utils.fromJSONString(content);
-    assertEquals("2", obj.get("id"));
-
     // TODO new test method
     String json = "{a:{" + "b:[{c:c1, e:e1},{c:c2, e :e2, d:{p:q}}]," + "x:y" + "}}";
     req = req("split", "/|/a/b");
@@ -338,6 +322,115 @@ public void testJsonDocFormat() throws Exception {
         p.addCommands.get(0).solrDoc.toString());
   }
 
+  public void testSrcAndUniqueDocs() throws Exception {
+    BufferingRequestProcessor p;
+    JsonLoader loader;
+    SolrQueryRequest req;
+    SolrQueryResponse rsp;
+    String doc;
+    String content;
+    Map<?, ?> src;
+    doc = "[{'id':'1','a':'b'},{'id':'2','c':'d'}]".replace('\'', '"');
+    boolean idOnly = random().nextBoolean();
+    boolean srcField = random().nextBoolean();
+    ModifiableSolrParams params = new ModifiableSolrParams();
+    if (idOnly) {
+      params.set("mapUniqueKeyOnly", "true");
+      params.set("df", "_catch_all");
+    }
+    if (srcField) {
+      params.set("srcField", "_src_");
+    }
+    req = req(params);
+    req.getContext().put("path", "/update/json/docs");
+    rsp = new SolrQueryResponse();
+    p = new BufferingRequestProcessor(null);
+    loader = new JsonLoader();
+    loader.load(req, rsp, new ContentStreamBase.StringStream(doc), p);
+    assertEquals(2, p.addCommands.size());
+
+    {
+      final SolrInputDocument doc1 = p.addCommands.get(0).solrDoc;
+      if (srcField) {
+        content = (String) doc1.getFieldValue("_src_");
+        assertNotNull(content);
+        src = (Map) Utils.fromJSONString(content);
+        assertEquals("1", src.get("id"));
+        assertEquals("b", src.get("a"));
+      } else {
+        assertFalse(doc1.containsKey("_src_"));
+      }
+      assertEquals("1", doc1.getFieldValue("id"));
+      if (idOnly) {
+        assertEquals(Arrays.asList("1", "b"), new ArrayList<>(doc1.getFieldValues("_catch_all")));
+        assertFalse(doc1.containsKey("a"));
+      } else {
+        assertEquals("b", doc1.getFieldValue("a"));
+        assertFalse(doc1.containsKey("_catch_all"));
+      }
+    }
+    {
+      final SolrInputDocument doc2 = p.addCommands.get(1).solrDoc;
+      if (srcField) {
+        content = (String) doc2.getFieldValue("_src_");
+        assertNotNull(content);
+        src = (Map) Utils.fromJSONString(content);
+        assertEquals("2", src.get("id"));
+        assertEquals("d", src.get("c"));
+      } else {
+        assertFalse(doc2.containsKey("_src_"));
+      }
+      assertEquals("2", doc2.getFieldValue("id"));
+      if (idOnly) {
+        assertEquals(Arrays.asList("2", "d"), new ArrayList<>(doc2.getFieldValues("_catch_all")));
+        assertFalse(doc2.containsKey("c"));
+      } else {
+        assertEquals("d", doc2.getFieldValue("c"));
+        assertFalse(doc2.containsKey("_catch_all"));
+      }
+    }
+  }
+
+  public void testEchoDocs() throws Exception {
+    BufferingRequestProcessor p;
+    JsonLoader loader;
+    SolrQueryRequest req;
+    SolrQueryResponse rsp;
+    String doc;
+
+    doc = "[{'id':'1'},{'id':'2'}]".replace('\'', '"');
+    boolean src = random().nextBoolean();
+    req = src ? req("srcField", "_src_", "echo", "true") : req("echo", "true");
+    req.getContext().put("path", "/update/json/docs");
+    rsp = new SolrQueryResponse();
+    p = new BufferingRequestProcessor(null);
+    loader = new JsonLoader();
+    loader.load(req, rsp, new ContentStreamBase.StringStream(doc), p);
+    assertEquals(0, p.addCommands.size());
+    @SuppressWarnings("unchecked")
+    final List<Map<String, String>> docs = (List<Map<String, String>>) rsp.getValues().get("docs");
+    assertNotNull(docs);
+    assertEquals(2, docs.size());
+    {
+      Map<String, String> doc1 = docs.get(0);
+      assertEquals("1", doc1.get("id"));
+      if (src) {
+        assertEquals("{\"id\":\"1\"}", doc1.get("_src_"));
+      } else {
+        assertFalse(doc1.containsKey("_src_"));
+      }
+    }
+    {
+      Map<String, String> doc2 = docs.get(1);
+      assertEquals("2", doc2.get("id"));
+      if (src) {
+        assertEquals("{\"id\":\"2\"}", doc2.get("_src_"));
+      } else {
+        assertFalse(doc2.containsKey("_src_"));
+      }
+    }
+  }
+
   private static final String PARENT_TWO_CHILDREN_JSON =
       "{\n"
           + "  \"id\": \"1\",\n"