When i try to append text to a log file, my log file becomes empty

i am trying to to check if a log file with the same name exist and if it does, i want to append in the current log file but if does not exist i want to make a new one with the current date when the app is running. The problem is when i try to append to my already existent log file, the log file becomes empty.

 string logFileLocation = Application.UserAppDataPath + "\\ cvDiagnostics_log_30-01-2022.text";

     StreamWriter logFileStream = new StreamWriter(new FileStream(logFileLocation, FileMode.Create));

     List<OutputEntry> outputMessages = new List<OutputEntry>();
     outputMessages.AddRange(logInfoOutputMessages);
     outputMessages.AddRange(logDebugOutputMessages);
     outputMessages.AddRange(logWarningOutputMessages);
     outputMessages.AddRange(logErrorOutputMessages);
     outputMessages = outputMessages.OrderBy(e => e.DisplayedTimeStamp).ToList();

     logFileStream.WriteLine( DateTime.Now.ToString());

     foreach (var message in outputMessages)
     {
        logFileStream.WriteLine(message.ToString());
     }

Here is my trying to check and append on an existing log file:

         if (File.Exists(logFileLocation))
     {
        File.AppendAllText(logFileLocation, outputMessages.ToString());
     }
  }
        else
        {
           File.Create(logFileLocation + DateTime.Now.ToString());
        }

>Solution :

To open the file, you open a FileStream with FileMode.Create. This will truncate the file if it already exists.

 StreamWriter logFileStream = new StreamWriter(new FileStream(logFileLocation, FileMode.Create));

Change this to:

 StreamWriter logFileStream = new StreamWriter(new FileStream(logFileLocation, FileMode.Append));

From the documentation on FileMode.Create:

"Specifies that the operating system should create a new file. If the file already exists, it will be overwritten. This requires Write permission. FileMode.Create is equivalent to requesting that if the file does not exist, use CreateNew; otherwise, use Truncate. If the file already exists but is a hidden file, an UnauthorizedAccessException exception is thrown."