diff --git a/routers/api/v1/repo/branch.go b/routers/api/v1/repo/branch.go
index 9f2ca69b89..00c8b68109 100644
--- a/routers/api/v1/repo/branch.go
+++ b/routers/api/v1/repo/branch.go
@@ -436,15 +436,11 @@ func UpdateBranch(ctx *context.APIContext) {
 		return
 	}
 
-	if ctx.Repo.GitRepo == nil {
-		ctx.APIErrorInternal(nil)
-		return
-	}
-
-	if err := repo_service.UpdateBranch(ctx, repo, ctx.Doer, branchName, opt.NewCommitID, opt.OldCommitID, opt.Force); err != nil {
+	// permission check has been done in api.go
+	if err := repo_service.UpdateBranch(ctx, repo, ctx.Repo.GitRepo, ctx.Doer, branchName, opt.NewCommitID, opt.OldCommitID, opt.Force); err != nil {
 		switch {
-		case git_model.IsErrBranchNotExist(err):
-			ctx.APIError(http.StatusNotFound, "Branch doesn't exist.")
+		case git.IsErrNotExist(err):
+			ctx.APIError(http.StatusUnprocessableEntity, err)
 		case repo_service.IsErrBranchCommitDoesNotMatch(err):
 			ctx.APIError(http.StatusConflict, err)
 		case git.IsErrPushOutOfDate(err):
@@ -452,10 +448,6 @@ func UpdateBranch(ctx *context.APIContext) {
 		case git.IsErrPushRejected(err):
 			rej := err.(*git.ErrPushRejected)
 			ctx.APIError(http.StatusForbidden, rej.Message)
-		case repo_model.IsErrUserDoesNotHaveAccessToRepo(err):
-			ctx.APIError(http.StatusForbidden, err)
-		case git.IsErrNotExist(err):
-			ctx.APIError(http.StatusUnprocessableEntity, err)
 		default:
 			ctx.APIErrorInternal(err)
 		}
diff --git a/services/repository/branch.go b/services/repository/branch.go
index 1e38cc7e9c..c15f9291a5 100644
--- a/services/repository/branch.go
+++ b/services/repository/branch.go
@@ -484,34 +484,10 @@ func RenameBranch(ctx context.Context, repo *repo_model.Repository, doer *user_m
 	return "", nil
 }
 
-// UpdateBranch moves a branch reference to the provided commit.
-func UpdateBranch(ctx context.Context, repo *repo_model.Repository, doer *user_model.User, branchName, newCommitID, expectedOldCommitID string, force bool) error {
-	if err := repo.MustNotBeArchived(); err != nil {
-		return err
-	}
-
-	perm, err := access_model.GetUserRepoPermission(ctx, repo, doer)
-	if err != nil {
-		return err
-	}
-	if !perm.CanWrite(unit.TypeCode) {
-		return repo_model.ErrUserDoesNotHaveAccessToRepo{
-			UserID:   doer.ID,
-			RepoName: repo.LowerName,
-		}
-	}
-
-	gitRepo, err := gitrepo.OpenRepository(ctx, repo)
-	if err != nil {
-		return fmt.Errorf("OpenRepository: %w", err)
-	}
-	defer gitRepo.Close()
-
+// UpdateBranch moves a branch reference to the provided commit. permission check should be done before calling this function.
+func UpdateBranch(ctx context.Context, repo *repo_model.Repository, gitRepo *git.Repository, doer *user_model.User, branchName, newCommitID, expectedOldCommitID string, force bool) error {
 	branchCommit, err := gitRepo.GetBranchCommit(branchName)
 	if err != nil {
-		if git.IsErrNotExist(err) {
-			return git_model.ErrBranchNotExist{RepoID: repo.ID, BranchName: branchName}
-		}
 		return err
 	}
 	currentCommitID := branchCommit.ID.String()