diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -741,12 +741,7 @@
         ProcessNewBlock(config, blockptr, /* fForceProcessing */ true,
                         /* fNewBlock */ &new_block);
     UnregisterValidationInterface(&sc);
-    if (!new_block) {
-        if (!accepted) {
-            // TODO Maybe pass down fNewBlock to AcceptBlockHeader, so it is
-            // properly set to true in this case?
-            return "invalid";
-        }
+    if (!new_block && accepted) {
         return "duplicate";
     }
 
diff --git a/test/functional/mining_basic.py b/test/functional/mining_basic.py
--- a/test/functional/mining_basic.py
+++ b/test/functional/mining_basic.py
@@ -43,6 +43,14 @@
     def run_test(self):
         node = self.nodes[0]
 
+        def assert_submitblock(block, result_str_1, result_str_2=None):
+            block.solve()
+            result_str_2 = result_str_2 or 'duplicate-invalid'
+            assert_equal(result_str_1, node.submitblock(
+                hexdata=b2x(block.serialize())))
+            assert_equal(result_str_2, node.submitblock(
+                hexdata=b2x(block.serialize())))
+
         self.log.info('getmininginfo')
         mining_info = node.getmininginfo()
         assert_equal(mining_info['blocks'], 200)
@@ -101,6 +109,8 @@
         bad_block = copy.deepcopy(block)
         bad_block.vtx.append(bad_block.vtx[0])
         assert_template(node, bad_block, 'bad-txns-duplicate')
+        assert_submitblock(bad_block, 'bad-txns-duplicate',
+                           'bad-txns-duplicate')
 
         self.log.info("getblocktemplate: Test invalid transaction")
         bad_block = copy.deepcopy(block)
@@ -109,12 +119,14 @@
         bad_tx.rehash()
         bad_block.vtx.append(bad_tx)
         assert_template(node, bad_block, 'bad-txns-inputs-missingorspent')
+        assert_submitblock(bad_block, 'bad-txns-inputs-missingorspent')
 
         self.log.info("getblocktemplate: Test nonfinal transaction")
         bad_block = copy.deepcopy(block)
         bad_block.vtx[0].nLockTime = 2 ** 32 - 1
         bad_block.vtx[0].rehash()
         assert_template(node, bad_block, 'bad-txns-nonfinal')
+        assert_submitblock(bad_block, 'bad-txns-nonfinal')
 
         self.log.info("getblocktemplate: Test bad tx count")
         # The tx count is immediately after the block header
@@ -134,18 +146,23 @@
         bad_block = copy.deepcopy(block)
         bad_block.hashMerkleRoot += 1
         assert_template(node, bad_block, 'bad-txnmrklroot', False)
+        assert_submitblock(bad_block, 'bad-txnmrklroot', 'bad-txnmrklroot')
 
         self.log.info("getblocktemplate: Test bad timestamps")
         bad_block = copy.deepcopy(block)
         bad_block.nTime = 2 ** 31 - 1
         assert_template(node, bad_block, 'time-too-new')
+        assert_submitblock(bad_block, 'time-too-new', 'time-too-new')
         bad_block.nTime = 0
         assert_template(node, bad_block, 'time-too-old')
+        assert_submitblock(bad_block, 'time-too-old', 'time-too-old')
 
         self.log.info("getblocktemplate: Test not best block")
         bad_block = copy.deepcopy(block)
         bad_block.hashPrevBlock = 123
         assert_template(node, bad_block, 'inconclusive-not-best-prevblk')
+        assert_submitblock(bad_block, 'prev-blk-not-found',
+                           'prev-blk-not-found')
 
         self.log.info('submitheader tests')
         assert_raises_rpc_error(-22, 'Block header decode failed',
@@ -155,6 +172,7 @@
         assert_raises_rpc_error(-25, 'Must submit previous header',
                                 lambda: node.submitheader(hexdata='ff' * 80))
 
+        block.nTime += 1
         block.solve()
 
         def chain_tip(b_hash, *, status='headers-only', branchlen=1):
@@ -176,7 +194,9 @@
         assert chain_tip(bad_block_root.hash) in node.getchaintips()
         # Should still reject invalid blocks, even if we have the header:
         assert_equal(node.submitblock(hexdata=b2x(
-            bad_block_root.serialize())), 'invalid')
+            bad_block_root.serialize())), 'bad-txnmrklroot')
+        assert_equal(node.submitblock(hexdata=b2x(
+            bad_block_root.serialize())), 'bad-txnmrklroot')
         assert chain_tip(bad_block_root.hash) in node.getchaintips()
         # We know the header for this invalid block, so should just return early without error:
         node.submitheader(hexdata=b2x(
@@ -189,7 +209,9 @@
         bad_block_lock.hashMerkleRoot = bad_block_lock.calc_merkle_root()
         bad_block_lock.solve()
         assert_equal(node.submitblock(hexdata=b2x(
-            bad_block_lock.serialize())), 'invalid')
+            bad_block_lock.serialize())), 'bad-txns-nonfinal')
+        assert_equal(node.submitblock(hexdata=b2x(
+            bad_block_lock.serialize())), 'duplicate-invalid')
         # Build a "good" block on top of the submitted bad block
         bad_block2 = copy.deepcopy(block)
         bad_block2.hashPrevBlock = bad_block_lock.sha256
@@ -222,6 +244,9 @@
         node.submitheader(hexdata=b2x(CBlockHeader(block).serialize()))
         node.submitheader(hexdata=b2x(
             CBlockHeader(bad_block_root).serialize()))
+        # valid
+        assert_equal(node.submitblock(hexdata=b2x(
+            block.serialize())), 'duplicate')
 
 
 if __name__ == '__main__':