diff --git a/core/rawdb/accessors_chain.go b/core/rawdb/accessors_chain.go
index 2f37cb051..320886c91 100644
--- a/core/rawdb/accessors_chain.go
+++ b/core/rawdb/accessors_chain.go
@@ -751,7 +751,7 @@ func FindCommonAncestor(db ethdb.Reader, a, b *types.WorkObject, nodeCtx int) (*
 	for bn := b.NumberU64(nodeCtx); a.NumberU64(nodeCtx) > bn; {
 		a = ReadHeader(db, a.NumberU64(nodeCtx)-1, a.ParentHash(nodeCtx))
 		if IsGenesisHash(db, a.ParentHash(nodeCtx)) {
-			return nil, fmt.Errorf("no common ancestor found")
+			return a, nil
 		}
 		if a == nil {
 			return nil, fmt.Errorf("unable to find hash %s", a.ParentHash(nodeCtx).String())
@@ -760,7 +760,7 @@ func FindCommonAncestor(db ethdb.Reader, a, b *types.WorkObject, nodeCtx int) (*
 	for an := a.NumberU64(nodeCtx); an < b.NumberU64(nodeCtx); {
 		b = ReadHeader(db, b.NumberU64(nodeCtx)-1, b.ParentHash(nodeCtx))
 		if IsGenesisHash(db, b.ParentHash(nodeCtx)) {
-			return nil, fmt.Errorf("no common ancestor found")
+			return b, nil
 		}
 		if b == nil {
 			return nil, fmt.Errorf("unable to find hash %s", b.ParentHash(nodeCtx).String())