Symptoms:
When BW executes FTP put or get activity it failed with below error,
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2017 Mar 08 21:36:57:644 GMT +0100 BW.GenericFileServer-GenericFileServer-050000-2 Error [General] EAI-03000 MSGID=9//QYszxfu-u/kn8J-/UKpw-JIg Error information
<ns0:ErrorReport xmlns:ns0="http://www.tibco.com/pe/EngineTypes">
    <StackTrace>Job-5032 Error in [GenericFileServer/Processes/GenericFileServer/sub_FTP_PUT.process/RetryOnError/putFile]
Error in PUT or MPUT command. See Error Tab for details.
        at com.tibco.plugin.ftp.FTPClient.putLocalFile(Unknown Source)
        at com.tibco.plugin.ftp.FTPTransport.ftpPutFileAsFile(Unknown Source)
        at com.tibco.plugin.ftp.FTPPutActivity.eval(Unknown Source)
        at com.tibco.pe.plugin.Activity.eval(Unknown Source)
        at com.tibco.pe.core.TaskImpl.eval(Unknown Source)
        at com.tibco.pe.core.Job.a(Unknown Source)
        at com.tibco.pe.core.Job.k(Unknown Source)
        at com.tibco.pe.core.JobDispatcher$JobCourier.a(Unknown Source)
        at com.tibco.pe.core.JobDispatcher$JobCourier.run(Unknown Source)
</StackTrace>
    <Msg>Error in PUT or MPUT command. See Error Tab for details.</Msg>
    <FullClass>com.tibco.plugin.ftp.PutFilesException</FullClass>
    <Class>PutFilesException</Class>
    <ProcessStack>GenericFileServer/Processes/GenericFileServer/TransferQueueFile.1.process/Process Publication&gt;GenericFileServer/Processes/GenericFileServer/Sub/Sub_TransferQueueFile.1.process/Group/FTP_PUT&gt;GenericFileServer/Processes/GenericFileServer/sub_FTP_PUT.process/RetryOnError/putFile</ProcessStack>
    <MsgCode>BW-FTP-100004</MsgCode>
    <Data>
        <PutFilesException>
            <SuccessfulFiles>None</SuccessfulFiles>
            <FailedFiles>
                <Filename>/LOG/tibco/FileTransfer/DWOS/9QYszxfu-ukn8J-UKpw-JIg_1489005197967_TransferFile_0011000044021126.txt</Filename>
                <Error>Unexpected reply code. Returned Code: 550. Detail Description: The system cannot find the path specified.  Expected Code: 125,150.</Error>
            </FailedFiles>
        </PutFilesException>
    </Data>
</ns0:ErrorReport>
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Cause:
Error itself self explanatory saying that BW is not able to locate specified file path or Path of file provided in input is not resolved and that caused the problem.

Looking at error message user think that it is related to local file that have provided in FTP activity input tab and complain that why its failing even if file is present on system or we can say that error mis-lead to local file input. But this is not the case always even if local file path is resolved and file is present on local system, BW may failed with same error and reason is "Remote File" provided in input. If Remote file provided path is not resolved then BW will failed with same exception.

FTP PUT, GET activity failed with error message while executing PUT or GET command on Remote FTP Server.

All

Check the 'RemoteFileName' input field in FTP activities and make sure that file path is valid. Same applies to 'LocalFileName' filed as well.
If one of the above field contain invalid file path or path is not resolved then it will failed with same error stack trace.