diff --git a/routers/repo/pull.go b/routers/repo/pull.go
index e4fd19ee49872..64bd8a03b8c7c 100644
--- a/routers/repo/pull.go
+++ b/routers/repo/pull.go
@@ -356,6 +356,16 @@ func PrepareViewPullInfo(ctx *context.Context, issue *models.Issue) *git.Compare
 		return nil
 	}
 	defer baseGitRepo.Close()
+
+	if !baseGitRepo.IsBranchExist(pull.BaseBranch) {
+		ctx.Data["IsPullRequestBroken"] = true
+		ctx.Data["BaseTarget"] = pull.BaseBranch
+		ctx.Data["HeadTarget"] = pull.HeadBranch
+		ctx.Data["NumCommits"] = 0
+		ctx.Data["NumFiles"] = 0
+		return nil
+	}
+
 	var headBranchExist bool
 	var headBranchSha string
 	// HeadRepo may be missing