[Python] flask - Python script returning KeyError when testing Login success screen

I'm making a Python script, opening a link that asks for a username and password and a login button which shows you your details, showing that the process have been completed. My problem is that, though the login page works, it gives a KeyError when I press the login button.

Here's my code:

from flask import Flask, request, redirect, url_for

app = Flask(__name__)

@app.route('/')
def RedirectToLogin():
return redirect(url_for('login'))

@app.route('/login', methods=['GET', 'POST'])
def login():
if request.method == 'POST':
username = request.form['username']
password = request.form['password']

return '''
<html>
<head>
<style>
.details-container {
display: flex;
justify-content: center;
align-items: center;
height: 100vh;
font-size: 24px;
text-align: center;
}
.form-container {
display: flex;
flex-direction: column;
width: 200px;
margin: 0 auto;
}
.form-input {
margin-bottom: 10px;
}
.smooth-button {
border-radius: 12px;
padding: 10px 20px;
background-color: black;
color: white;
border: none;
cursor: pointer;
margin-top: 20px;
}
.smooth-button:hover {
background-color: #45a049;
}
</style>
</head>
<body>
<div class="details-container">
<div>
<p>Username: {0}</p>
<p>Password: {1}</p>
</div>
</div>
</body>
</html>
'''.format(username, password)

return '''
<html>
<head>
<style>
.form-container {
display: flex;
flex-direction: column;
width: 200px;
margin: 0 auto;
}

.form-input {
margin-bottom: 10px;
}

.smooth-button {
border-radius: 12px;
padding: 10px 20px;
background-color: black;
color: white;
border: none;
cursor: pointer;
margin-top: 20px;
}

.smooth-button:hover {
background-color: #45a049;
}
</style>
</head>
<body>
<form method="post" action="/login" class="form-container">
<label for="username">Username:</label>
<input type="text" id="username" name="username" class="form-input"><br>

<label for="password">Password:</label>
<input type="password" id="password" name="password" class="form-input"><br>
<input type="submit" value="Login" class="smooth-button">
</form>
</body>
</html>
'''

if __name__ == '__main__':
app.run(debug=True)

What I expected:


Username: [User input for username]
Password: [User input for password]

[Login] <---- button

Username: [Inputted username]
Password: [Inputted password]

What I got


Username: [User input for username]
Password: [User input for password]

[Login] <---- button

## KeyError ##
KeyError: '\n display'

Traceback (most recent call last)
File "C:\Users\ABC\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.11_qbz5n2kfra8p0\LocalCache\local-packages\Python311\site-packages\flask\app.py", line 1498, in __call__

return self.wsgi_app(environ, start_response)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File "C:\Users\ABC\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.11_qbz5n2kfra8p0\LocalCache\local-packages\Python311\site-packages\flask\app.py",

line 1476, in wsgi_app

response = self.handle_exception(e)
^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\ABC\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.11_qbz5n2kfra8p0\LocalCache\local-packages\Python311\site-packages\flask\app.py",

line 1473, in wsgi_app

response = self.full_dispatch_request()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\ABC\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.11_qbz5n2kfra8p0\LocalCache\local-packages\Python311\site-packages\flask\app.py",

line 882, in full_dispatch_request

rv = self.handle_user_exception(e)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\ABC\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.11_qbz5n2kfra8p0\LocalCache\local-packages\Python311\site-packages\flask\app.py",

line 880, in full_dispatch_request

rv = self.dispatch_request()
^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\ABC\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.11_qbz5n2kfra8p0\LocalCache\local-packages\Python311\site-packages\flask\app.py",

line 865, in dispatch_request
return self.ensure_sync(self.view_functions[rule.endpoint])(**view_args) # type: ignore[no-any-return]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "c:\Users\ABC\Desktop\VsCode Projects\Python Projects\Login-Page-with-Flask.py",

line 59, in login
'''.format(username, password)
^^^^^^^^^^^^^^^^^^^^^^^^^^Open an interactive python shell in this frame
KeyError: '\n display'
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How to resolve this?

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