Intermittent non-specific exception from GetListingInternal()

[carden-jeremy]

I do daily checks of a public FTP folder to look for updated weather data, and sometimes, FluentFtp throws an exception when I call GetListing(). We have logged 77 of these exceptions since March 2025. When it works successfully, the recursive query currently returns 21,609 files.

I realize the problem could be the fault of the FTP server, but I'd appreciate it if we could get a more clear exception message from FluentFtp than "Object reference not set to an instance of an object".

Path to the FTP I'm trying to list recursively:
ftp.cpc.ncep.noaa.gov/precip/CPC_UNI_PRCP/GAUGE_CONUS/V1.0/

Exception:

Message: Object reference not set to an instance of an object.

   at FluentFTP.AsyncFtpClient.GetListingInternal(String listcmd, FtpListOption options, Boolean retry, CancellationToken token)
   at FluentFTP.AsyncFtpClient.GetListing(String path, FtpListOption options, CancellationToken token)
   at FluentFTP.AsyncFtpClient.GetListingRecursive(String path, FtpListOption options, CancellationToken token)
   at FluentFTP.AsyncFtpClient.GetListing(String path, FtpListOption options, CancellationToken token)
   at FtpClientTools.GetListOfFilesOnFtpAsync(String fullPathToFtpFolder, Boolean recursive, String username, String password)

My code:

bool recursive = true;
FtpListItem[] fileListing = await myAsyncFtpClient.GetListing(ftpPath, recursive ? FtpListOption.Recursive : FtpListOption.Auto);

FluentFtp v53.0.1

Thank you

[FanDjango]

You made me do a bit of work in order to test this. Why such a terse problem description?

I had to assume the FTP server is "ftp.cpc.ncep.noaa.gov"
The path is then "precip/CPC_UNI_PRCP/GAUGE_CONUS/V1.0/"

No Encryption.

Anyway, a recursive GetListing works fine if doing it with the SYNC client. Using the ASYNC client, I can confirm that the above mentioned exception will occur.

There must be some bug in the ASYNC client.

[FanDjango]

In my tests, this happens every time, not intermittently, so that may ease finding the problem.

[carden-jeremy]

My apologies for sounding terse. I didn't know what else to include except the code, FTP path, exception, stack trace, and background info. I could have provided a console app to reproduce, but since it's intermittent (for me), I didn't think it would help. Thank you for this project and your assistance.

[FanDjango]

Anyway, reproducible for me, so we've got a good chance. I'll look into it ASAP.

[FanDjango]

Oh, my bad.

I accidentaly did not "await" the getlisting call in the async test I put together, quickly edited to change it from sync to async. Sorry.

Interestingly, this actually caused exactly the error you described, you may try this also if you like.

Without the await, my using block will destruct the client while waiting for a reply to a command, causing this failure.

This "sort of thing" must also be happening intermittently, the client being destroyed on account of some deep down error that is not handled correctly.

Now, with the await if works as with the sync client.

So I suppose I need to retry many times? It would help if you could indicate the frequency of the error appearing?

[FanDjango]

Also, after poring over the code, I really think it would be nice to have a verbose log of the failure and the commands preceeding it.

Maybe we are not handling some (intermittent) failure of the server correctly.

[carden-jeremy]

Since it happens intermittently, roughly 1-2 times per week, it could be something like FTP server maintenance or heavy traffic periods, so retrying many times in a row may not help.

I've added a FluentFtp FtpLogger to capture all the verbose logs. If the error happens again, it should send me the logs, and I'll add those here.

[carden-jeremy]

Here's my full function. I added the verbose logging and auto-retry behavior today.

public static async Task<List<FtpFileInfo>> GetListOfFilesOnFtpAsync(string fullPathToFtpFolder, bool recursive, string? username = null, string? password = null)
{
    string ftpHostname = PathParser.GetHostNameFromUrl(fullPathToFtpFolder);
    string pathToFolderWithinHost = PathParser.GetPathToFolderWithoutHostname(fullPathToFtpFolder);

    // convert file timestamps on the server from UTC to the local EST
    FtpConfig ftpConfig = new()
    {
        TimeConversion = FtpDate.LocalTime,
        LocalTimeZone = -5,
        TimeZone = 0
    };

    int numTries = 0;
    int maxNumTries = 5;
    List<Exception> exceptionsCaught = new();

    while (numTries <= maxNumTries)
    {
        numTries++;

        FtpVerboseLogger ftpLogger = new();

        try
        {
            using (AsyncFtpClient ftpClient = new(ftpHostname, config: ftpConfig))
            {
                if (!string.IsNullOrEmpty(username))
                {
                    ftpClient.Credentials = new NetworkCredential(username, password);
                }

                ftpClient.Logger = ftpLogger;

                _ = await ftpClient.AutoConnect();

                List<FtpFileInfo> lstRemoteFiles = new();

                FtpListItem[] fileListing = await ftpClient.GetListing(pathToFolderWithinHost, recursive ? FtpListOption.Recursive : FtpListOption.Auto);

                foreach (FtpListItem item in fileListing)
                {
                    string fullRemotePath = ftpHostname + item.FullName;
                    if (item.Type == FtpObjectType.Directory)
                    {
                        // make sure directory paths always end with a backslash
                        fullRemotePath = fullRemotePath.TrimEnd('/') + '/';
                    }

                    lstRemoteFiles.Add(new()
                    {
                        FileSubPath = item.FullName,
                        FullRemoteFilePath = fullRemotePath,
                        FileSize = item.Size,
                        IsFolder = item.Type == FtpObjectType.Directory,
                        LastWriteTime = item.Modified
                    });
                }

                return lstRemoteFiles;
            }
        }
        catch (Exception ex)
        {

            // remove all Listing entries except the first and last 20
            List<FtpLogEntry> listingEntries = ftpLogger.logs
                .Where(e => e.Severity == FtpTraceLevel.Verbose && e.Message.StartsWith("Listing:", StringComparison.OrdinalIgnoreCase))
                .ToList();

            HashSet<FtpLogEntry> toKeep = new HashSet<FtpLogEntry>(
                listingEntries.Take(20)
                              .Concat(listingEntries.Skip(listingEntries.Count - 20))
            );

            int numberEntriesRemoved = listingEntries.Count - toKeep.Count;

            List<FtpLogEntry> filteredLogsToReport = ftpLogger.logs
                .Where(e =>
                    !(e.Severity == FtpTraceLevel.Verbose && e.Message.StartsWith("Listing:", StringComparison.OrdinalIgnoreCase))
                    || toKeep.Contains(e))
                .ToList();

            StringBuilder sb = new();
            foreach (FtpLogEntry log in filteredLogsToReport)
            {
                sb.AppendLine($"{log.Severity}: {log.Message}");

                if (log.Exception != null)
                {
                    sb.AppendLine($"\n\nException: {log.Exception}\n\n");
                }
            }

            Exception exWithVerboseLogs = new($"An exception was caught while trying to read from FTP server \"{fullPathToFtpFolder}\". Here are the verbose logs from the FTP client ({numberEntriesRemoved.ToString("N0")} \"Listing:\" lines were removed to reduce log size):\n\n{sb.ToString()}", ex);

            exceptionsCaught.Add(exWithVerboseLogs);

            // TODO: THIS IS TEMPORARY TO HELP US CAPTURE AN ERROR FROM THE FTP LIBRARY AND REPORT IT TO FLUENTFTP ISSUE# 1776.
            if (ex.Message.Contains("Object reference not set to an instance of an object"))
            {
                throw exWithVerboseLogs;
            }
        }

        // wait a moment before retrying to avoid overloading the remote server
        await Task.Delay(2000);
    }

    // if we get here, the loop failed to return a list of files and ran out of tries, so throw the last exception we caught
    throw new Exception($"Failed to get list of files from remote server \"{fullPathToFtpFolder}\" after {maxNumTries} attempts.", exceptionsCaught.Last());
}

[FanDjango]

Ok, I've looked over the code some more.

The only "object" instances we could have lost somehow, are the datastream and the controlstream. Losing the datastream is something we actually cater for, many servers terminate it aggressively themselves from their side when a transfer is ended.

Losing the control stream, though: It seems we are perhaps not catching all possible things that might have gone wrong.

The log will tell us more.

Then I could put some more debugging into GetListing. Are you restricted to using the Nuget package or would you be able to use a modified FluentFTP from a repo?

[carden-jeremy]

I'd like to capture the verbose logs from the current version if we can, and then if you want me to run a custom build to investigate further, I'm happy to help. I'm currently waiting for the next error to happen - hopefully it doesn't suddenly start working perfectly for the next 3 months.

[carden-jeremy]

I think I captured one this morning at 8:01 AM EST for the first time since creating this ticket. Note that my logger removes many of the "Listing" lines to reduce the size of the message.

---------------------- Exception Details, Chain [1.1] ----------------------
Exception Type: System.Exception
Exception Message: An exception was caught while trying to read from FTP server "[ftp.cpc.ncep.noaa.gov/precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/](ftp://ftp.cpc.ncep.noaa.gov/precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/)". Here are the verbose logs from the FTP client (888 "Listing:" lines were removed to reduce log size):

Info: >         AutoConnect()
Info: >         AutoDetect(CloneConnection = False, FirstOnly = True, IncludeImplicit = True, AbortOnTimeout = True, RequireEncryption = False, ProtocolPriority = [Tls12])
Verbose: Auto-Detect trying encryption mode "Auto" with protocol "Tls12"
Info: >         Connect(False)
Verbose: FluentFTP 53.0.1.0(.NET 8.0) AsyncFtpClient
Verbose: Connecting(async) AsyncFtpClient.FtpSocketStream(control) IP #1 = ***:21
Verbose: Waiting for a response
Verbose: Response: 220-******************************************************************
Response: **WARNING**WARNING**WARNING**
Response: This is a United States (Agency) computer system, which may be accessed
Response: and used only for official Government business by authorized personnel.
Response: Unauthorized access or use of this computer system may subject violators
Response: to criminal, civil, and/or administrative action.
Response: All information on this computer system may be intercepted, recorded,
Response: read, copied, and disclosed by and to authorized personnel for official
Response: purposes, including criminal investigations. Access or use of this
Response: computer system by any person whether authorized or unauthorized,
Response: constitutes consent to these terms.
Response: **WARNING**WARNING**WARNING**
Response: ******************************************************************
Info: Response: 220  [739511.5d]
Info: Command:  AUTH TLS
Verbose: Waiting for response to: AUTH TLS
Info: Response: 500 AUTH not understood [42ms]
Info: Command:  USER ***
Verbose: Waiting for response to: USER ***
Info: Response: 331 Anonymous login ok, send your complete email address as your password [41ms]
Info: Command:  PASS ***
Verbose: Waiting for response to: PASS ***
Info: Response: 230 Login successful. [50ms]
Info: Command:  FEAT
Verbose: Waiting for response to: FEAT
Verbose: Response: 211-Features:
Response: CLNT
Response: EPRT
Response: EPSV
Response: HOST
Response: LANG bg-BG;en-US;es-ES;fr-FR;it-IT;ja-JP;ko-KR;ru-RU;zh-CN;zh-TW
Response: MDTM
Response: MFF modify;UNIX.group;UNIX.mode;
Response: MFMT
Response: MLST modify*;perm*;size*;type*;unique*;UNIX.group*;UNIX.groupname*;UNIX.mode*;UNIX.owner*;UNIX.ownername*;
Response: REST STREAM
Response: SIZE
Response: TVFS
Response: UTF8
Info: Response: 211 End [83ms]
Info: Text encoding: System.Text.UTF8Encoding+UTF8EncodingSealed
Info: Command:  OPTS UTF8 ON
Verbose: Waiting for response to: OPTS UTF8 ON
Info: Response: 200 UTF8 set to on [42ms]
Info: Command:  SYST
Verbose: Waiting for response to: SYST
Info: Response: 215 UNIX Type: L8 [41ms]
Verbose: Active ServerHandler is: None
Verbose: Listing parser set to: Machine
Info: Command:  PWD
Verbose: Waiting for response to: PWD
Info: Response: 257 "/" is the current directory [41ms]
Info: >         GetListing("/precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED", Auto)
Info: Command:  TYPE I
Verbose: Waiting for response to: TYPE I
Info: Response: 200 Type set to I [41ms]
Info: >         OpenDataStreamAsync("MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED", 0)
Info: >         OpenPassiveDataStreamAsync(PASV, "MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED", 0)
Info: Command:  PASV
Verbose: Waiting for response to: PASV
Info: Response: 227 Entering Passive Mode (***,***,***,***,255,136). [42ms]
Verbose: Connecting(async) AsyncFtpClient.FtpSocketStream(data) IP #1 = ***:65416
Info: Command:  MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED
Verbose: Waiting for response to: MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED
Info: Response: 150 Opening BINARY mode data connection for MLSD [46ms]
Verbose: +---------------------------------------+
Verbose: Listing:  modify=20250322002650;perm=fle;type=cdir;unique=3CU4ED33E6;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0755;UNIX.owner=2034;UNIX.ownername=ftp; .
Verbose: Listing:  modify=20090306184749;perm=fle;type=pdir;unique=3CU4ED33ED;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0775;UNIX.owner=2000;UNIX.ownername=ftp; ..
Verbose: Listing:  modify=20200226221433;perm=fle;type=dir;unique=3CU4ED33E7;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0755;UNIX.owner=2034;UNIX.ownername=ftp; 2019
Verbose: Listing:  modify=20210303154618;perm=fle;type=dir;unique=3CU4F9FB30;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0755;UNIX.owner=2034;UNIX.ownername=ftp; 2020
Verbose: Listing:  modify=20220222170736;perm=fle;type=dir;unique=3CU4F7E6CC;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0755;UNIX.owner=2034;UNIX.ownername=ftp; 2021
Verbose: Listing:  modify=20210317143026;perm=fle;type=dir;unique=3CU4F7E6CD;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0755;UNIX.owner=2034;UNIX.ownername=ftp; DOCU
Verbose: Listing:  modify=20230221150318;perm=fle;type=dir;unique=3CU4FF05C4;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0755;UNIX.owner=2034;UNIX.ownername=ftp; 2022
Verbose: Listing:  modify=20240321023732;perm=fle;type=dir;unique=3CU4EB6D8C;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0755;UNIX.owner=2034;UNIX.ownername=ftp; 2023
Verbose: Listing:  modify=20250220145135;perm=fle;type=dir;unique=3CU4FC5EF8;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0755;UNIX.owner=2034;UNIX.ownername=ftp; 2024
Verbose: Listing:  modify=20250901151725;perm=fle;type=dir;unique=3CU4F867A8;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0755;UNIX.owner=2034;UNIX.ownername=ftp; 2025
Verbose: -----------------------------------------
Verbose: Disposing(async) AsyncFtpClient.FtpSocketStream(data)
Info: >         CloseDataStream()
Verbose: Waiting for response to: MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED
Info: Response: 226 Transfer complete [98ms]
Verbose: Disposing(async) AsyncFtpClient.FtpSocketStream(data) (redundant)
Info: >         GetListing("/precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2025", Auto)
Info: >         OpenDataStreamAsync("MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2025", 0)
Info: >         OpenPassiveDataStreamAsync(PASV, "MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2025", 0)
Info: Command:  PASV
Verbose: Waiting for response to: PASV
Info: Response: 227 Entering Passive Mode (***,***,***,***,255,169). [41ms]
Verbose: Connecting(async) AsyncFtpClient.FtpSocketStream(data) IP #1 = ***:65449
Info: Command:  MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2025
Verbose: Waiting for response to: MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2025
Info: Response: 150 Opening BINARY mode data connection for MLSD [43ms]
Verbose: +---------------------------------------+
Verbose: Listing:  modify=20250901151725;perm=fle;type=cdir;unique=3CU4F867A8;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0755;UNIX.owner=2034;UNIX.ownername=ftp; .
Verbose: Listing:  modify=20250322002650;perm=fle;type=pdir;unique=3CU4ED33E6;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0755;UNIX.owner=2034;UNIX.ownername=ftp; ..
Verbose: Listing:  modify=20250322010614;perm=adfr;size=288000;type=file;unique=3CU4F86ED4;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20250101.UPDATED
Verbose: Listing:  modify=20250322010614;perm=adfr;size=288000;type=file;unique=3CU4F86ED5;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20250102.UPDATED
Verbose: Listing:  modify=20250322010614;perm=adfr;size=288000;type=file;unique=3CU4F86ED6;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20250103.UPDATED
Verbose: Listing:  modify=20250322010614;perm=adfr;size=288000;type=file;unique=3CU4F86ED7;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20250104.UPDATED
Verbose: Listing:  modify=20250322010614;perm=adfr;size=288000;type=file;unique=3CU4F86ED8;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20250105.UPDATED
Verbose: Listing:  modify=20250322010614;perm=adfr;size=288000;type=file;unique=3CU4F86ED9;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20250106.UPDATED
Verbose: Listing:  modify=20250322010614;perm=adfr;size=288000;type=file;unique=3CU4F86EDA;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20250107.UPDATED
Verbose: Listing:  modify=20250322010614;perm=adfr;size=288000;type=file;unique=3CU4F86EDB;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20250108.UPDATED
Verbose: -----------------------------------------
Verbose: Disposing(async) AsyncFtpClient.FtpSocketStream(data)
Info: >         CloseDataStream()
Verbose: Waiting for response to: MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2025
Info: Response: 226 Transfer complete [153ms]
Verbose: Disposing(async) AsyncFtpClient.FtpSocketStream(data) (redundant)
Info: >         GetListing("/precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2024", Auto)
Info: >         OpenDataStreamAsync("MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2024", 0)
Info: >         OpenPassiveDataStreamAsync(PASV, "MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2024", 0)
Info: Command:  PASV
Verbose: Waiting for response to: PASV
Info: Response: 227 Entering Passive Mode (***,***,***,***,255,187). [41ms]
Verbose: Connecting(async) AsyncFtpClient.FtpSocketStream(data) IP #1 = ***:65467
Info: Command:  MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2024
Verbose: Waiting for response to: MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2024
Info: Response: 150 Opening BINARY mode data connection for MLSD [43ms]
Verbose: +---------------------------------------+
Verbose: Listing:  modify=20250322002650;perm=fle;type=pdir;unique=3CU4ED33E6;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0755;UNIX.owner=2034;UNIX.ownername=ftp; ..
Verbose: -----------------------------------------
Verbose: Disposing(async) AsyncFtpClient.FtpSocketStream(data)
Info: >         CloseDataStream()
Verbose: Waiting for response to: MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2024
Info: Response: 226 Transfer complete [205ms]
Verbose: Disposing(async) AsyncFtpClient.FtpSocketStream(data) (redundant)
Info: >         GetListing("/precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2023", Auto)
Info: >         OpenDataStreamAsync("MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2023", 0)
Info: >         OpenPassiveDataStreamAsync(PASV, "MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2023", 0)
Info: Command:  PASV
Verbose: Waiting for response to: PASV
Info: Response: 227 Entering Passive Mode (***,***,***,***,255,202). [43ms]
Verbose: Connecting(async) AsyncFtpClient.FtpSocketStream(data) IP #1 = ***:65482
Info: Command:  MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2023
Verbose: Waiting for response to: MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2023
Info: Response: 150 Opening BINARY mode data connection for MLSD [48ms]
Verbose: +---------------------------------------+
Verbose: Listing:  modify=20250322002650;perm=fle;type=pdir;unique=3CU4ED33E6;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0755;UNIX.owner=2034;UNIX.ownername=ftp; ..
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4F01364;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231212.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4F01365;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231213.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4F01366;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231214.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4F01367;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231215.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FBC;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231216.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FBD;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231217.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FBE;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231218.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FBF;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231219.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FC0;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231220.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FC1;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231221.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FC2;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231222.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FC3;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231223.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FC4;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231224.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FC5;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231225.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FC6;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231226.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FC7;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231227.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FC8;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231228.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4C46FC9;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231229.UPDATED
Verbose: Listing:  modify=20240315011636;perm=adfr;size=288000;type=file;unique=3CU4CA14EA;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231230.UPDATED
Verbose: Listing:  modify=20240315011637;perm=adfr;size=288000;type=file;unique=3CU4CA14EB;UNIX.group=2000;UNIX.groupname=ftp;UNIX.mode=0644;UNIX.owner=2034;UNIX.ownername=ftp; PRCP_CU_GAUGE_V1.0CONUS_0.25deg.lnx.20231231.UPDATED
Verbose: -----------------------------------------
Verbose: Disposing(async) AsyncFtpClient.FtpSocketStream(data)
Info: >         CloseDataStream()
Verbose: Waiting for response to: MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2023
Info: Response: 226 Transfer complete [205ms]
Verbose: Disposing(async) AsyncFtpClient.FtpSocketStream(data) (redundant)
Info: >         GetListing("/precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2022", Auto)
Info: >         OpenDataStreamAsync("MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2022", 0)
Info: >         OpenPassiveDataStreamAsync(PASV, "MLSD /precip/CPC_UNI_PRCP/GAUGE_CONUS/UPDATED/2022", 0)
Info: Command:  PASV
Verbose: Waiting for response to: PASV
Verbose: Disposing(async) AsyncFtpClient.FtpSocketStream(control)
Verbose: Disposing(async) AsyncFtpClient.FtpSocketStream(control) (redundant)
Verbose: GetReply(...) failure: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host..
Info: >         Dispose()
Verbose: Warning: sync dispose called for AsyncFtpClient object
Info: >         DisposeAsync()
Verbose: Disposing(async) AsyncFtpClient
Info: >         Disconnect()
Verbose: Connection already closed, nothing to do.


---------------------- Exception Details, Chain [1.1.1] ----------------------
Exception Type: System.NullReferenceException
Exception Message: Object reference not set to an instance of an object.

Exception Stack Trace:
   at FluentFTP.AsyncFtpClient.GetListingInternal(String listcmd, FtpListOption options, Boolean retry, CancellationToken token)
   at FluentFTP.AsyncFtpClient.GetListing(String path, FtpListOption options, CancellationToken token)
   at FluentFTP.AsyncFtpClient.GetListingRecursive(String path, FtpListOption options, CancellationToken token)
   at FluentFTP.AsyncFtpClient.GetListing(String path, FtpListOption options, CancellationToken token)
   at FTPTools.FtpClientTools.GetListOfFilesOnFtpAsync(String fullPathToFtpFolder, Boolean recursive, String username, String password) in FTPClientTools.cs:line 48

---------------------- End ----------------------