python - 即使模板文件存在，Flask也会引发TemplateNotFound错误

您必须在正确的位置创建模板文件。在templates您的python模块旁边的子目录中。

The error indicates that there is no home.html file in the templates/ directory. Make sure you created that directory in the same directory as your python module, and that you did in fact put a home.html file in that subdirectory. If your app is a package, the templates folder should be created inside the package.

myproject/
    app.py
    templates/
        home.html

myproject/
    mypackage/
        __init__.py
        templates/
            home.html

Alternatively, if you named your templates folder something other than templates and don't want to rename it to the default, you can tell Flask to use that other directory.

app = Flask(__name__, template_folder='template')  # still relative to module

You can ask Flask to explain how it tried to find a given template, by setting the EXPLAIN_TEMPLATE_LOADING option to True. For every template loaded, you'll get a report logged to the Flask app.logger, at level INFO.

搜索成功后的样子：在此示例中，foo/bar.html模板扩展了base.html模板，因此有两个搜索：

[2019-06-15 16:03:39,197] INFO in debughelpers: Locating template "foo/bar.html":
    1: trying loader of application "flaskpackagename"
       class: jinja2.loaders.FileSystemLoader
       encoding: 'utf-8'
       followlinks: False
       searchpath:
         - /.../project/flaskpackagename/templates
       -> found ('/.../project/flaskpackagename/templates/foo/bar.html')
[2019-06-15 16:03:39,203] INFO in debughelpers: Locating template "base.html":
    1: trying loader of application "flaskpackagename"
       class: jinja2.loaders.FileSystemLoader
       encoding: 'utf-8'
       followlinks: False
       searchpath:
         - /.../project/flaskpackagename/templates
       -> found ('/.../project/flaskpackagename/templates/base.html')

蓝图也可以注册自己的模板目录，但这不是必需的，如果您使用蓝图可以更轻松地在逻辑单元之间拆分较大的项目。即使在每个蓝图中使用其他路径，也始终会首先搜索Flask应用程序主模板目录。