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    Object Storage Service:FAQ

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    Object Storage Service:FAQ

    Last Updated:Jun 21, 2026

    This topic provides answers to some frequently asked questions about ossftp.

    Failed connection to the FTP server

    • Symptom

      Note: The error message returned because the server failed to be connected. 

      Response:	331 Username ok, send password.
Command:	PASS ***************************
Response:	530 Can't list buckets, check your access_key.request_id:569db7b4aec9a1c34e0aaaff, status:403, code:accessdenied, message:accessdenied
Error:	Critical error: Cannot connect to server

    • Cause

      • The AccessKey ID or AccessKey Secret is incorrect.

      • The RAM user associated with the AccessKey pair lacks the required permissions to access OSS.

    • Resolution

      • Enter the correct AccessKey ID and AccessKey Secret and try to connect to the server again.

      • Grant the required permissions to the RAM user based on your use case.

        The following section describes the required permissions for a RAM user in common scenarios:

        • Read-only access to objects in an OSS bucket

          Required permissions: oss:ListObjects and oss:GetObject

        • Write data to an OSS bucket

          Required permissions: oss:ListObjects and oss:PutObject

        • Delete data from a bucket

          Required permissions: oss:ListObjects and oss:DeleteObject

        For more information about how to grant RAM users permissions in other scenarios, see Common examples of RAM policies.

    501 error returned when you use FileZilla to connect to the FTP server

    • Symptom

      You receive a 501 error when you run an FTP server on Linux and then use FileZilla to connect to the server.

      501 can't decode path (server filesystem encoding is ANSI_X3.4-1968)

    • Cause

      The Chinese characters are not properly encoded.

    • Resolution

      1. In the terminal where you plan to run the start.sh script, run the following command:

        $ export LC_ALL=en_US.UTF-8; export LANG="en_US.UTF-8"; locale

      2. Restart FileZilla.

    Disconnections due to timeout that occurs when you list objects after you log on to ossftp

    A large number of objects and directories are stored in the root directory of the bucket. After you log on to ossftp, the FTP server attempts to list all objects and directories in the root directory of the bucket. Up to 1,000 objects and directories can be listed at a time. If more than 1 million objects and directories are stored in the root directory, more than 1,000 requests are sent to list the objects and directories and therefore timeout occurs.

    Failed data transmission

    • Cause

      The control port and the data port of the FTP server are different. When the FTP server needs to transfer data in passive mode, a port is randomly selected and enabled for connections to the client. When the machine that runs the FTP server has port limits, data may fail to be transferred.

    • Resolution

      When you run ftpserver.py, use the --passive_ports_start and --passive_ports_end options to define a port range. Then, ensure the ports in this range are open.

    Frequent disconnections between the client and the FTP server

    • Cause

      The connection between the client and the FTP server times out.

    • Resolution

      Specify that the connection between the client and the FTP Server does not time out. For example, choose Settings > Connection in FileZilla and then set the timeout period to 0.