I try to access a subdirectory, and my FTP software reports a 451 Internal Error, what's going on?

If your FTP client software (e.g. WS_FTP LE) reports something like the following and crashes:

451 Internal error
! Retrieve of folder listing failed (4)

then most likely the cause of the problem is the fact that you have too many files in the subdirectory (i.e. folder) that you are trying to access. Please note that it's a VERY BAD practice to put excessive amounts of files in a subdirectory. We will discuss this in depth, below.

Your FTP software also is partially to blame too. Its internal limit for the number of directory listing entries may be too small. In this case switching to a better FTP client, such as NcFTP Client may allow you to show the HUGE listing without crashing.

Please also note that your problem has nothing to do with our hosting services. As stated above, it's caused by a combination of user content creation/maintenance mistakes and the built-in limitation of your FTP software.

Now lets talk about the problem of putting too many files in a subdirectory (i.e. folder). If you think about it, would it be really messy if you put thousands of paper files into one document folder? Computer files are just counterparts of their paper ones, and so is a subdirectory to a paper document folder. So, just because you deal with computer files, you still need to keep the number of files in a subdirectory under a reasonable limit, and arrange them in a fairly neat order. Computers won't do such tasks for you. That job is up to you, the content creator and maintainer!

To avoid such problems in the future, please always keep our above advice in mind: never put too many (e.g. several hundreds or thousands) files in one subdirectory (i.e. folder).

Should you have any questions in this regard, please contact AZC Technical Support at

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