Here are some potential causes and troubleshooting steps based on the information you've provided:

1. Redirect Issue:

    Check for URL Redirect: Code 301 indicates a permanent redirect. Ensure you're using the correct API address or adjust your request to follow the redirect.
    Verify API Endpoint: Double-check the API endpoint documentation for any changes in the address or authentication logic.

2. Authentication Problem:

    Review Authentication Requirements: Carefully examine the API documentation for specific authentication parameters and their expected formats.
    Validate Data: Ensure the rand_int, auth_string, and other fields in your data dictionary match the requirements exactly.
    Check Credentials: Verify that the get_username and get_password methods are returning accurate credentials for this API.
    Consider Hash Algorithm: If the API expects a different hash algorithm, update the code accordingly.

3. Server-Side Issue:

    Consult Server Logs: If possible, examine server logs for more details about the "Invalid argument" error.
    Explore Server Configuration: Review server configuration for potential restrictions or authentication requirements.

Additional Troubleshooting:

    Inspect Network Traffic: Use a tool like Wireshark or Fiddler to visualize the request and response details, potentially revealing errors or inconsistencies.
    Debug Code: Add print statements or use a debugger to examine variable values and execution flow.
    Consult API Documentation: Carefully re-read the API documentation for any missing or misunderstood requirements.
    Seek Community Help: If available, consider forums or support channels for the API or authentication framework you're using.

Recommendations:

    Provide More Context: If possible, share relevant snippets from API documentation, server-side error details, and any additional code for further analysis.
    Follow Best Practices:
        Use descriptive variable names and comments for better readability.
        Employ error handling mechanisms to catch potential exceptions and provide informative messages.
        Organize code into logical functions for modularity and maintainability.

Here are some potential causes and troubleshooting steps based on the information you've provided:

1. Redirect Issue:

    Check for URL Redirect: Code 301 indicates a permanent redirect. Ensure you're using the correct API address or adjust your request to follow the redirect.
    Verify API Endpoint: Double-check the API endpoint documentation for any changes in the address or authentication logic.

2. Authentication Problem:

    Review Authentication Requirements: Carefully examine the API documentation for specific authentication parameters and their expected formats.
    Validate Data: Ensure the rand_int, auth_string, and other fields in your data dictionary match the requirements exactly.
    Check Credentials: Verify that the get_username and get_password methods are returning accurate credentials for this API.
    Consider Hash Algorithm: If the API expects a different hash algorithm, update the code accordingly.

3. Server-Side Issue:

    Consult Server Logs: If possible, examine server logs for more details about the "Invalid argument" error.
    Explore Server Configuration: Review server configuration for potential restrictions or authentication requirements.

Additional Troubleshooting:

    Inspect Network Traffic: Use a tool like Wireshark or Fiddler to visualize the request and response details, potentially revealing errors or inconsistencies.
    Debug Code: Add print statements or use a debugger to examine variable values and execution flow.
    Consult API Documentation: Carefully re-read the API documentation for any missing or misunderstood requirements.
    Seek Community Help: If available, consider forums or support channels for the API or authentication framework you're using.

Recommendations:

    Provide More Context: If possible, share relevant snippets from API documentation, server-side error details, and any additional code for further analysis.
    Follow Best Practices:
        Use descriptive variable names and comments for better readability.
        Employ error handling mechanisms to catch potential exceptions and provide informative messages.
        Organize code into logical functions for modularity and maintainability.