Hey there! I’ve run into this exact problem before—let me break down what’s going wrong and how to fix it quickly.

The Root Cause #

When you use file.readline(), it doesn’t just grab the text on the line—it also includes the newline character (\n) at the end of each line. For example, if your data.txt looks like this:

exampleusername
examplepassword
example@example.com
2018

Your username variable ends up being "exampleusername\n" instead of the clean "exampleusername" you hardcoded earlier. That extra newline throws off the website’s validation, which is why you’re seeing that error.

Quick Fixes #

Here are a few straightforward ways to fix this:

1. Strip whitespace from each line
   Use the strip() method to remove newline characters, spaces, and tabs from the start/end of each read value:

   with open("data.txt", "r") as file:
       username = file.readline().strip()
       password = file.readline().strip()
       email = file.readline().strip()
       year = file.readline().strip()
   

   (I used a with statement here because it automatically closes the file for you—no need to remember file.close()!)

2. Read all lines at once and clean them
   If you prefer, you can read all lines in one go, then process them:

   with open("data.txt", "r") as file:
       # Read all lines, strip whitespace, and filter out any empty lines
       lines = [line.strip() for line in file if line.strip()]
       username, password, email, year = lines
   

   This is handy if your file might have blank lines you want to skip.

3. Check what you’re actually reading
   If you’re still stuck, print the raw values to see hidden characters. Use repr() to show exactly what’s in the variable:

   print(repr(username))  # Will show "exampleusername\n" if the newline is present
   

   This helps confirm if the newline is the culprit.

Bonus Tip #

Make sure your data.txt doesn’t have any extra spaces or blank lines at the start/end—those can cause issues too. The strip() method takes care of most of that, but it’s good to double-check the file content.

内容的提问来源于stack exchange，提问作者neminem