错误[ERR_HTTP_HEADERS_SENT]：将标头发送到客户端Nodejs后无法设置标头

Question

我是Node.js的新手，我正在编写代码以通过post方法更新Firebase中的详细信息，同时更新时我会得到

Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
    at ServerResponse.setHeader (_http_outgoing.js:526:11)
    at ServerResponse.header (G:\xampp_new\htdocs\saiby\public\node_modules\express\lib\response.js:771:10)
    at ServerResponse.send (G:\xampp_new\htdocs\saiby\public\node_modules\express\lib\response.js:170:12)
    at done (G:\xampp_new\htdocs\saiby\public\node_modules\express\lib\response.js:1008:10)
    at tryHandleCache (G:\xampp_new\htdocs\saiby\public\node_modules\ejs\lib\ejs.js:261:5)
    at View.exports.renderFile [as engine] (G:\xampp_new\htdocs\saiby\public\node_modules\ejs\lib\ejs.js:461:10)
    at View.render (G:\xampp_new\htdocs\saiby\public\node_modules\express\lib\view.js:135:8)
    at tryRender (G:\xampp_new\htdocs\saiby\public\node_modules\express\lib\application.js:640:10)
    at Function.render (G:\xampp_new\htdocs\saiby\public\node_modules\express\lib\application.js:592:3)
    at ServerResponse.render (G:\xampp_new\htdocs\saiby\public\node_modules\express\lib\response.js:1012:7)**

我一步一步地完成了调试，我唯一能发现的就是在执行Firebase更新功能之前，nodejs到达/执行到功能底部，然后又回到了Firebase功能中。

我已经附上了调试步骤，输出的内容可供参考，任何人都可以指出此代码出了什么问题。 TIA

app.post('/update_project', function(req, res) {
    console.log(" update_project ");    

    var project_id = req.body.project_id;
    var project_name = req.body.project_name;
    var project_survey_Date = req.body.project_survey_Date;
    var project_location = req.body.project_location;
    var project_user_Mobile_No = req.body.project_user_Mobile_No;
    var project_Assigned_to = req.body.project_Assigned_to;
    var project_status = req.body.project_status;
    var project_image = req.body.image;
    var Mark_as_Completed = req.body.Mark_as_Completed;



    if (Mark_as_Completed != undefined) {
        Mark_as_Completed = 'yes';
    } else {
        Mark_as_Completed = 'no';
    }

    if (project_id != '' && project_name != '' && project_survey_Date != '' && project_location != '' && project_user_Mobile_No != '') {
        var db = admin.database();
        var projectsref = db.ref("projects/" + project_id);

        if (project_image != undefined && project_image != '') {
            projectsref.update({
                project_image: project_image
            });
            console.log(" update_project 123");
        }

        console.log(" update_project 43ftgerfgref4ef");

        try {

            projectsref.update({
                project_name: project_name,
                project_Visiting_Date: project_survey_Date,
                project_location: project_location,
                project_user_Mobile_No: project_user_Mobile_No,
                project_Assigned_to: project_Assigned_to,
                project_status: project_status,
                Mark_as_Completed: Mark_as_Completed,
            }).then(function() {
                console.log("called Then ");
                return res.redirect('/projects');
            }).catch(function(error) {
                console.log("Data could not be saved." + error);
            });
            return; 

        } catch (error) {
            console.log(" Error : 483 " + error);
        }
        console.log(" try catch ends");         
    }
    console.log(" fiukll outer ");     
});

输出