Django 常见错误

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环境信息

  • centos7
  • python3
  • Django 4

ModuleNotFoundError: No module named ‘MySQLdb’

ModuleNotFoundError: No module named ‘MySQLdb’
…
django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module.

解决方法

pip3 install pymysql

编辑文件./python36/lib/python3.6/site-packages/django/db/backends/mysql/__init__.py, 输入以下内容

import pymysql 
pymysql.install_as_MySQLdb()

django.core.exceptions.ImproperlyConfigured

使用以下命令启动服务时报错

django-admin runserver

django.core.exceptions.ImproperlyConfigured: Requested setting DEBUG, but settings are not configured. You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings

解决方法

使用命令
python3 manage.py runserver

because its MIME type (‘text/html’) is not a supported stylesheet MIME type

css 文件路径配置错误，访问文件 404

环境信息

  • centos7
  • python3.10
  • uwsgi 2.0.20
  • venv

ModuleNotFoundError: No module named ‘django’

uwsgi 启动后报错(查看 uwsgi 日志输出)

from django.core.wsgi import get_wsgi_application  
ModuleNotFoundError: No module named 'django'

解决方法

uwsgi 配置文件(uwsgi.ini )中添加 python 路径, 在配置文件中添加如下配置：

uwsgi.ini
pythonpath = /env/lib/python3.10/site-packages/

完整 uwsgi 配置文件示例(使用 python venv 模块创建虚拟环境情况下)：

[uwsgi]
socket = 127.0.0.1:8081
chdir = /opt/vb/vb
wsgi-file = ./vb/wsgi.py
master = true         //主进程
vhost = true          //多站模式
no-site = true        //多站模式时不设置入口模块和文件
workers = 2           //子进程数
reload-mercy = 10     
vacuum = true         //退出、重启时清理文件
max-requests = 1000   
limit-as = 512
buffer-size = 30000
pidfile = uwsgi-8081.pid
daemonize = uwsgi-8081.log
pythonpath = /opt/vb/env/lib/python3.10/site-packages/

unable to load app 0

uwsgi 启动后报错(查看 uwsgi 日志输出)

unable to load app 0 (mountpoint='|') (callable not found or import error)  
--- no python application found, check your startup logs for errors ---

解决方法

uwsgi 配置文件(uwsgi.ini )中添加 wsgi.py 路径, 在配置文件中添加如下配置：

uwsgi.ini
wsgi-file = ./project/wsgi.py

django.db.utils.OperationalError

项目根目录执行 python manage.py migrate 时报错 django.db.utils.OperationalError: (1366, "Incorrect string value: '\\xE6\\x9C\\x8D\\xE5\\x8A\\xA1...' for column 'name' at row 1")

排查步骤

  1. 查看数据库编码设置

    mysql> show variables like "%char%";
    +--------------------------+----------------------------+
    | Variable_name            | Value                      |
    +--------------------------+----------------------------+
    | character_set_client     | utf8                       |
    | character_set_connection | utf8                       |
    | character_set_database   | latin1                     |
    | character_set_filesystem | binary                     |
    | character_set_results    | utf8                       |
    | character_set_server     | latin1                     |
    | character_set_system     | utf8                       |
    | character_sets_dir       | /usr/share/mysql/charsets/ |
    +--------------------------+----------------------------+
    8 rows in set (0.01 sec)

  2. 修改数据库编码为 utf8

    修改数据库配置文件 my.cnf，添加以下配置

    [mysqld]

    character-set-server = utf8
    collation-server=utf8_general_ci

    重启数据库，检查编码设置

    mysql> show variables like "%char%";

    +--------------------------+----------------------------+
    | Variable_name            | Value                      |
    +--------------------------+----------------------------+
    | character_set_client     | utf8                       |
    | character_set_connection | utf8                       |
    | character_set_database   | utf8                       |
    | character_set_filesystem | binary                     |
    | character_set_results    | utf8                       |
    | character_set_server     | utf8                       |
    | character_set_system     | utf8                       |
    | character_sets_dir       | /usr/share/mysql/charsets/ |
    +--------------------------+----------------------------+
    8 rows in set (0.05 sec)

  3. 重新执行 python manage.py migrate 依旧返回同样的报错，检查之前创建的数据库编码

    mysql> show create database mydb;
    +-----------------+----------------------------------------------------------------------------+
    | Database        | Create Database                                                            |
    +-----------------+----------------------------------------------------------------------------+
    | mydb | CREATE DATABASE `mydb` /*!40100 DEFAULT CHARACTER SET latin1 */ |
    +-----------------+----------------------------------------------------------------------------+
    1 row in set (0.00 sec)

    编码显示为 latin1，删除数据库重新创建

    mysql> drop database mydb;
    Query OK, 12 rows affected (0.10 sec)

    mysql> create database mydb;
    Query OK, 1 row affected (0.00 sec)

    mysql> show create database mydb;
    +-----------------+--------------------------------------------------------------------------+
    | Database        | Create Database                                                          |
    +-----------------+--------------------------------------------------------------------------+
    | mydb | CREATE DATABASE `mydb` /*!40100 DEFAULT CHARACTER SET utf8 */ |
    +-----------------+--------------------------------------------------------------------------+
    1 row in set (0.00 sec)

    新建的数据库编码为 utf8，重新执行 python manage.py makemigrations，python manage.py migrate，执行成功。删除数据库重建后，如若使用后台，需要为后台重新生成 superuser。

环境信息

  • Python 3.11.2
  • Django==4.1.7
  • mysqlclient==2.1.1

django.db.utils.NotSupportedError: MariaDB 10.3 or later is required (found 5.5.68)

解决方法：

在 /usr/local/lib/python3.11/site-packages/django/db/backends/base/base.py 中搜索 self.check_database_version_supported，然后把这一行注释掉。

sed -i 's/self.check_database_version_supported/#self.check_database_version_supported/' /usr/local/lib/python3.11/site-packages/django/db/backends/base/base.py

Raised by: django.contrib.admin.sites.catch_all_view

在项目的入口 urls.py 文件中按照以下配置，应用 cloud_client 对应的 url （/cloud_client/）无法匹配到，抛出异常信息： Raised by: django.contrib.admin.sites.catch_all_view

urls.py
from django.contrib import admin
from django.urls import path, include

urlpatterns = [
   path('', admin.site.urls),
   path('cloud_client/', include('cloud_client.urls')),
    
]

参考文章说明，修改为以下配置后，应用相关的 url 访问正常，自定义的 URls 需要在 admin 的 URLs 之前。 [1]

urls.py
from django.contrib import admin
from django.urls import path, include

urlpatterns = [
   
   path('cloud_client/', include('cloud_client.urls')),
   path('', admin.site.urls),
]

Key ‘id’ not found in ‘xxx’. Choices are: xxx

Django admin 后台中点击报错，错误原因为模型注册到后台时，fields 配置中包含了 id 字段，因为字段 id 设置的自增 ID 键，在数据库中对应的是 AUTO_INCREMENT，所以这个字段是不允许编辑的，而 fields 这个配置设置是可编辑字段，导致冲突，所以会报错。 [2]

Refused to execute script from ‘‘ because its MIME type (‘text/html’) is not executable, and strict MIME type checking is enabled

Django 配置 DEBUG = False 后，页面访问异常

Django admin 静态资源 404

请求中，admin 页面的所有资源显示 404

"GET /static/admin/js/core.js HTTP/1.1" 404 179

原因是因为关闭了 DEBUG 模式（通过配置 DEBUG = False），所以导致找不到静态资源。生产环境中需要关闭 DEBUG，需要给 Django 的静态资源配置路由来解决。 [3]

The Cross-Origin-Opener-Policy header has been ignored

浏览器加载页面报错

The Cross-Origin-Opener-Policy header has been ignored, because the URL's origin was untrustworthy. It was defined either in the final response or a redirect. Please deliver the response using the HTTPS protocol. You can also use the 'localhost' origin instead. See https://www.w3.org/TR/powerful-features/#potentially-trustworthy-origin and https://html.spec.whatwg.org/#the-cross-origin-opener-policy-header.


Django 4 的安全机制。调试环境在配置文件 settings.py 中配置以下参数即可解决

settings.py
SECURE_CROSS_ORIGIN_OPENER_POLICY = 'None'

read of closed file

Django 中用户从 Web 页面中点击下载文件，Django 对文件压缩并返回给客户端。前端页面代码如下：

<a href="{% url 'client:download_certificate' certificate_name=domain.Certificate_Name %}">Download Certificate</a>

其中的 domain.Certificate_Name 是要传送给下载 url 的证书名称变量。

url 如下：

urls.py
from django.urls import path
from cloudclient import views



app_name = 'client'

urlpatterns = [
    path('download_certificate/<str:certificate_name>/', views.download_certificate, name='download_certificate'),


]

视图函数（views.py） 关键代码如下：

views.py
from django.shortcuts import render, HttpResponse
from django.http import FileResponse, Http404
from django.contrib.auth.decorators import login_required
from django.conf import settings

def download_certificate(request, certificate_name):
    certificate_dir = os.path.join(settings.BASE_DIR, f'data/letsencrypt/live/{certificate_name}')
    logging.info(f"ssl download: {certificate_dir}")
    certificate_zip = f'{certificate_dir}.zip'

    if os.path.exists(certificate_zip):
        os.remove(certificate_zip)
        logging.info(f"ssl certificate zip file {certificate_zip} exists. Delete it before compress")

    # 压缩文件夹函数
    zip_directory(certificate_dir, f'{certificate_dir}.zip')
    logging.info(f"compress file {certificate_zip} END!")

    if os.path.exists(certificate_zip):
        # 打开文件并发送给用户
        logging.info(f"compress file {certificate_zip} EXISTS! Began send to client.")
        with open(certificate_zip, 'rb') as f:
            logging.info(f"Open compressed certificate file {certificate_zip} and send to client")
            response = FileResponse(f)
            response['Content-Disposition'] = f'attachment; filename={certificate_name}.zip'
            logging.info(f"response info: {str(response)}")
            return response

    else:
        # 如果文件不存在，返回 404 错误
        logging.error(f"ssl download file: {certificate_zip} NOT exists!")
        raise Http404("File not found")

使用以上代码后，用户在 Web 页面中点击 Download Certificate 进行证书下载，Web 页面显示 A server error occurred. Please contact the administrator.， 检查下载链接响应码为 500。

检查代码输出的日志信息，最后包含 response info: <FileResponse status_code=200, "application/zip">，说明代码处理到此处无异常。

检查 Django 的终端输出日志，看到以下错误：

response info: <FileResponse status_code=200, "application/zip">
Traceback (most recent call last):
  File "/usr/local/lib/python3.11/wsgiref/handlers.py", line 138, in run
    self.finish_response()
  File "/usr/local/lib/python3.11/wsgiref/handlers.py", line 183, in finish_response
    for data in self.result:
  File "/usr/local/lib/python3.11/wsgiref/util.py", line 24, in __next__
    data = self.filelike.read(self.blksize)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ValueError: read of closed file

根据错误信息 ValueError: read of closed file，问题很可能出在文件处理逻辑上。错误发生在尝试从一个已经关闭的文件中读取数据，这通常发生在使用 with 语句打开文件后，文件自动关闭，但 Django 的 FileResponse 对象仍尝试从这个文件流中读取数据。

在 Django 中使用 FileResponse 返回一个文件给客户端时，需要确保文件在响应对象完成发送数据后再关闭。在上面的代码中，文件通过 with 语句打开，因此在 with 代码块结束时自动关闭了文件。这导致 FileResponse 在尝试访问已关闭的文件时失败。

为解决这个问题，可以修改文件打开的方式，确保文件在整个请求处理过程中保持开放。下面是修正后的代码：

def ssl_download_certificate(request, certificate_name):
    certificate_dir = os.path.join(settings.BASE_DIR, f'data/letsencrypt/live/{certificate_name}')
    logging.info(f"ssl download: {certificate_dir}")
    certificate_zip = f'{certificate_dir}.zip'

    if os.path.exists(certificate_zip):
        os.remove(certificate_zip)
        logging.info(f"ssl certificate zip file {certificate_zip} exists. Delete it before compress")

    zip_directory(certificate_dir, f'{certificate_dir}.zip')
    logging.info(f"compress file {certificate_zip} END!")

    if os.path.exists(certificate_zip):
        # 打开文件并发送给用户
        logging.info(f"compress file {certificate_zip} EXISTS! Began send to client.")
        f = open(certificate_zip, 'rb')  # 打开文件，不立即关闭
        logging.info(f"Open compressed certificate file {certificate_zip} and send to client")
        response = FileResponse(f, as_attachment=True, filename=f"{certificate_name}.zip")
        logging.info(f"response info: {str(response)}")
        return response
        # with open(certificate_zip, 'rb') as f:
        #     logging.info(f"Open compressed certificate file {certificate_zip} and send to client")
        #     response = FileResponse(f)
        #     response['Content-Disposition'] = f'attachment; filename={certificate_name}.zip'
        #     logging.info(f"response info: {str(response)}")
        #     return response

    else:
        # 如果文件不存在，返回 404 错误
        logging.error(f"ssl download file: {certificate_zip} NOT exists!")
        raise Http404("File not found")

修改为以上代码后，文件下载正常。

环境信息

  • Centos 7 3.10.0-1160
  • Python 3.6
  • Django 3.2.25

启动 Django Server 时报错，关键信息 django.core.exceptions.ImproperlyConfigured: SQLite 3.9.0 or later is required (found 3.7.17).：

File "/opt/python3_web/lib64/python3.6/site-packages/django/db/utils.py", line 111, in load_backend
    return import_module('%s.base' % backend_name)
  File "/usr/lib64/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "/opt/python3_web/lib64/python3.6/site-packages/django/db/backends/sqlite3/base.py", line 73, in <module>
    check_sqlite_version()
  File "/opt/python3_web/lib64/python3.6/site-packages/django/db/backends/sqlite3/base.py", line 69, in check_sqlite_version
    'SQLite 3.9.0 or later is required (found %s).' % Database.sqlite_version
django.core.exceptions.ImproperlyConfigured: SQLite 3.9.0 or later is required (found 3.7.17).

根据错误信息可知是系统上安装的 SQLite 版本不满足。参考以下命令安装最新版本 SQLite

wget https://www.sqlite.org/2024/sqlite-autoconf-3460100.tar.gz
tar -xf sqlite-autoconf-3460100.tar.gz
cd sqlite-autoconf-3460100
./configure --prefix=/usr/local/
make
make install

如果不需要使用 SQLite，可以不用安装升级 ，可以根据提示修改文件 python3.6/site-packages/django/db/backends/sqlite3/base.py 中的函数 check_sqlite_version，使其跳过版本检查。

def check_sqlite_version():
    if Database.sqlite_version_info < (3, 6, 0):
        raise ImproperlyConfigured(
            'SQLite 3.9.0 or later is required (found %s).' % Database.sqlite_version
        )


check_sqlite_version()

脚注