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FTP Error 503 Login Authentication Failed

Yesterday while trying to access my web hosting account, I received an error message "503 Login Authentication Failed". I have been using FireFTP as my FTP client for one year and I never faced such an issue. I had been using FileZilla before migrating to FireFTP but it never showed such a problem. However, I do not believe it is an issue with FireFTP. I have checked the username, password and host address once again but they are correct. I tried to log in to web host account a few more times but received the same error. One time it showed a different alert with the same code. The new popup was "503 Login error". This tutorial explains the reasons and solution of "503 Login Authentication Failed". Since I was in a hurry, I couldn't troubleshoot the issue by myself. I deleted the entire FTP cache and entered the FTP server access details manually once again. This time I didn't face any trouble to access the web server. I have saved the screenshot of the popup I received.

Today morning I started searching for more about this message. In many discussion forums, experts say "503 Login Authentication Failed" is due to the incorrect username or password. You may get the alert if the host address is typed wrongly. Another possibility is the usage of Caps Lock without knowing that key is on while entering username and password. Anyway, after clearing the cache of my FTP program (deleted previously saved username, password and host address), I successfully logged in to my server ftp account.

Solution For FTP Error 503 Login Authentication Failed

The reason for 503 Login Authentication Failed: An FTP error occurred - cannot make connection to host is the incorrect File Transfer Protocol login information.

  • Port Number should be 21 (FTP server use port number 21 to transfer files).

  • Host address, FTP username, and password should be correct

  • Make sure Caps Lock is turned off

  • If still the problem is not fixed, clear the cache

PS: Clearing cache means delete all stored FireFTP usernames, passwords, and host addresses. This procedure cannot be undone, so make sure you have the backup of the necessary details you entered.

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cvrt03 said…
How to delete ftp cache?
Anand said…
by simply using delete button we can delete selected ftp username and details from ftp cache..
Outbound email filtering said…
Deleting the FTP cache clears out the error 503

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Alex George
Alex George has Engineering graduation in Computer Science and an MBA in Finance. He had been working as a senior Network Engineer for ten years. His specialization is in Cisco products. Traveling is one of his hobbies and visited various places as part of his onsite work. He visited different places as part of his onsite work like New York, Dubai, London, etc. Right now Alex is a director of one of the leading career development firms in India, which trains students for UPSC, SSC, and PSC examinations. He guides a lot of students to get selection for various prestigious institutions like CBI, Income Tax Department, etc. Alex George is a stock market investor and a very active intraday trader. Engineering Background: He has a B.Tech in Computer Science and Engineering and passed different network and security courses like CCNA, CCNP (Security), CEH, and various Microsoft certifications. Finance Background: Alex has an MBA in Finance. He is an active intraday trader and a Share Market Investor. Webmaster Skills: Alex is a blogger since 2004. He has a working knowledge of HTML, CSS, PHP, and JavaScrip.