diff --git a/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapreduce/TableOutputFormat.java b/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapreduce/TableOutputFormat.java
index 4eb26541d04..78be5af1bf4 100644
--- a/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapreduce/TableOutputFormat.java
+++ b/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapreduce/TableOutputFormat.java
@@ -174,9 +174,9 @@ implements Configurable {
   @Override
   public void checkOutputSpecs(JobContext context) throws IOException,
       InterruptedException {
-    Configuration hConf = context.getConfiguration();
+    Configuration hConf = getConf();
     if (hConf == null) {
-      hConf = this.conf;
+      hConf = context.getConfiguration();
     }
 
     try (Admin admin = ConnectionFactory.createConnection(hConf).getAdmin()) {
diff --git a/hbase-spark/src/test/scala/org/apache/hadoop/hbase/spark/TableOutputFormatSuite.scala b/hbase-spark/src/test/scala/org/apache/hadoop/hbase/spark/TableOutputFormatSuite.scala
new file mode 100644
index 00000000000..b306f081099
--- /dev/null
+++ b/hbase-spark/src/test/scala/org/apache/hadoop/hbase/spark/TableOutputFormatSuite.scala
@@ -0,0 +1,130 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.spark
+
+
+import java.text.SimpleDateFormat
+import java.util.{Date, Locale}
+
+import org.apache.hadoop.hbase.mapreduce.TableOutputFormat
+import org.apache.hadoop.hbase.{HBaseTestingUtility, TableName, TableNotFoundException}
+import org.apache.hadoop.hbase.util.Bytes
+import org.apache.hadoop.mapreduce.{Job, TaskAttemptID, TaskType}
+import org.apache.hadoop.mapreduce.task.TaskAttemptContextImpl
+import org.apache.spark.{SparkConf, SparkContext}
+import org.scalatest.{BeforeAndAfterAll, BeforeAndAfterEach, FunSuite}
+
+import scala.util.{Failure, Success, Try}
+
+
+// Unit tests for HBASE-20521: change get configuration(TableOutputFormat.conf) object first sequence from jobContext to getConf
+// this suite contains two tests, one for normal case(getConf return null, use jobContext), create new TableOutputformat object without init TableOutputFormat.conf object,
+// configuration object inside checkOutputSpecs came from jobContext.
+// The other one(getConf return conf object) we manually call "setConf" to init TableOutputFormat.conf, for making it more straight forward, we specify a nonexistent table
+// name in conf object, checkOutputSpecs will then throw TableNotFoundException exception
+class TableOutputFormatSuite extends FunSuite with
+  BeforeAndAfterEach with BeforeAndAfterAll with Logging{
+  @transient var sc: SparkContext = null
+  var TEST_UTIL = new HBaseTestingUtility
+
+  val tableName = "TableOutputFormatTest"
+  val tableNameTest = "NonExistentTable"
+  val columnFamily = "cf"
+
+  override protected def beforeAll(): Unit = {
+    TEST_UTIL.startMiniCluster
+
+    logInfo(" - minicluster started")
+    try {
+      TEST_UTIL.deleteTable(TableName.valueOf(tableName))
+    }
+    catch {
+      case e: Exception => logInfo(" - no table " + tableName + " found")
+    }
+
+    TEST_UTIL.createTable(TableName.valueOf(tableName), Bytes.toBytes(columnFamily))
+    logInfo(" - created table")
+
+    //set "validateOutputSpecs" true anyway, force to validate output spec
+    val sparkConf = new SparkConf()
+      .setMaster("local")
+      .setAppName("test")
+
+    sc = new SparkContext(sparkConf)
+  }
+
+  override protected def afterAll(): Unit = {
+    logInfo(" - delete table: " + tableName)
+    TEST_UTIL.deleteTable(TableName.valueOf(tableName))
+    logInfo(" - shutting down minicluster")
+    TEST_UTIL.shutdownMiniCluster()
+
+    TEST_UTIL.cleanupTestDir()
+    sc.stop()
+  }
+
+  def getJobContext() = {
+    val hConf = TEST_UTIL.getConfiguration
+    hConf.set(TableOutputFormat.OUTPUT_TABLE, tableName)
+    val job = Job.getInstance(hConf)
+    job.setOutputFormatClass(classOf[TableOutputFormat[String]])
+
+    val jobTrackerId = new SimpleDateFormat("yyyyMMddHHmmss", Locale.US).format(new Date())
+    val jobAttemptId = new TaskAttemptID(jobTrackerId, 1, TaskType.MAP, 0, 0)
+    new TaskAttemptContextImpl(job.getConfiguration, jobAttemptId)
+  }
+
+  // Mock up jobContext object and execute actions in "write" function
+  // from "org.apache.spark.internal.io.SparkHadoopMapReduceWriter"
+  // this case should run normally without any exceptions
+  test("TableOutputFormat.checkOutputSpecs test without setConf called, should return true and without exceptions") {
+    val jobContext = getJobContext()
+    val format = jobContext.getOutputFormatClass
+    val jobFormat = format.newInstance
+    Try {
+      jobFormat.checkOutputSpecs(jobContext)
+    } match {
+      case Success(_) => assert(true)
+      case Failure(_) => assert(false)
+    }
+  }
+
+  // Set configuration externally, checkOutputSpec should use configuration object set by "SetConf" method
+  // rather than jobContext, this case should throw "TableNotFoundException" exception
+  test("TableOutputFormat.checkOutputSpecs test without setConf called, should throw TableNotFoundException") {
+    val jobContext = getJobContext()
+    val format = jobContext.getOutputFormatClass
+    val jobFormat = format.newInstance
+
+    val hConf = TEST_UTIL.getConfiguration
+    hConf.set(TableOutputFormat.OUTPUT_TABLE, tableNameTest)
+    jobFormat.asInstanceOf[TableOutputFormat[String]].setConf(hConf)
+    Try {
+      jobFormat.checkOutputSpecs(jobContext)
+    } match {
+      case Success(_) => assert(false)
+      case Failure(e: Exception) => {
+        if(e.isInstanceOf[TableNotFoundException])
+          assert(true)
+        else
+          assert(false)
+      }
+    }
+  }
+
+}