Python/Django报错指向错误行？KeyError定位异常排查

使用Django + Python 3.9，访问路由/myapp/myroute时触发KeyError at /myapp/myroute，提示了对应的键值，但错误堆栈指向第929行的else:语句，并非实际出错位置。

相关代码 #

# this is the path to the main image
if "filename" in request.session:
    if "file_url" in request.session:
        ip = request.session["file_url"]
    # error here - this is line 925 in my code
    else:
        s3 = boto3.client('s3')
        ip = f"""{request.session["iam"]}/image/{request.session["filename"]}"""
        request.session["file_url"] = ip

    if ip != us.ImagePath:
        change = True
else:
    return redirect("index")

s3r = boto3.resource("s3")
obj = None

if "qrp" not in request.session:
    request.session["qrp"] = ""

try:
    request.session["qrp"] = f"""{request.session["iam"]}/sub_image/{str(request.session["usid"])}.png"""
    obj = s3r.Object('iet-ticket-bucket', qrfn)
    obj.load()
except botocore.exceptions.ClientError as e:
    if e.response["Error"]["Code"] == "404":

img = q.make(json.dumps({"id": request.session["usid"], "storename": ""}))
iba = io.BytesIO()
img.save(iba, format="PNG")
s3 = boto3.client('s3')
s3.put_object(Bucket="iet-ticket-bucket", Key=request.session["qrp"], Body=iba.getvalue(), ContentType="image/png")
request.session["qrp"] = qrp
change = True

# where the error should be
qrp = request.session["qrp"]

堆栈跟踪信息 #

Traceback (most recent call last):
   File "/home/ec2-user/django/django/core/handlers/exception.py", line 55, in inner
     response = get_response(request)
   File "/home/ec2-user/django/django/core/handlers/base.py", line 197, in _get_response
     response = wrapped_callback(request, *callback_args, **callback_kwargs)
   File "/home/ec2-user/DjangoProjects/appws/app/views.py", line 926, in thank_you
     else:
   File "/home/ec2-user/django/django/contrib/sessions/backends/base.py", line 53, in __getitem__
     return self._session[key]
 KeyError: 'qrp'

排查结果 #

经排查，问题根源在于服务器部署在Apache后，仅执行systemctl start httpd而非systemctl restart httpd重启服务，导致代码更新不彻底，错误行显示异常。实际错误发生在qrp = request.session["qrp"]行。

内容的提问来源于stack exchange，提问作者Shmack