Reading and parsing text file exception-C# - winforms

Question

I am parsing big text files and it's working fine for some time but after few minutes it give me exception (An unhandled exception of type 'System.UnauthorizedAccessException' occurred in System.Core.dll
Additional information: Access to the path is denied.)
I get exception on below mention line.
accessor = MemoryMapped.CreateViewAccessor(offset, length, MemoryMappedFileAccess.Read);
Below is my function
public static void CityStateZipAndZip4(string FilePath,long offset,long length,string spName)
{
try
{
long indexBreak = offset;
string fileName = Path.GetFileName(FilePath);
if (fileName.Contains(".txt"))
fileName = fileName.Replace(".txt", "");
System.IO.FileStream file = new System.IO.FileStream(#FilePath, FileMode.Open,FileAccess.Read, FileShare.Read );
Int64 b = file.Length;
MemoryMappedFile MemoryMapped = MemoryMappedFile.CreateFromFile(file, fileName, b, MemoryMappedFileAccess.Read, null, HandleInheritability.Inheritable, false);
using (MemoryMapped)
{
//long offset = 182; // 256 megabytes
//long length = 364; // 512 megabytes
MemoryMappedViewAccessor accessor = MemoryMapped.CreateViewAccessor(offset, length, MemoryMappedFileAccess.Read);
byte byteValue;
int index = 0;
int count = 0;
StringBuilder message = new StringBuilder();
do
{
if (indexBreak == index)
{
count = count + 1;
accessor.Dispose();
string NewRecord = message.ToString();
offset = offset + indexBreak;
length = length + indexBreak;
if (NewRecord.IndexOf("'") != -1)
{ NewRecord = NewRecord.Replace("'", "''"); }
// string Sql = "insert into " + DBTableName + " (ID, DataString) values( " + count + ",'" + NewRecord + "')";
string Code = "";
if (spName == AppConfig.sp_CityStateZip)
{
Code = NewRecord.Trim().Substring(0, 1);
}
InsertUpdateAndDeleteDB(spName, NewRecord.Trim (), Code);
accessor = MemoryMapped.CreateViewAccessor(offset, length, MemoryMappedFileAccess.Read);
message = new StringBuilder();
index = 0;
//break;
}
byteValue = accessor.ReadByte(index);
if (byteValue != 0)
{
char asciiChar = (char)byteValue;
message.Append(asciiChar);
}
index++;
} while (byteValue != 0);
}
MemoryMapped.Dispose();
}
catch (FileNotFoundException)
{
Console.WriteLine("Memory-mapped file does not exist. Run Process A first.");
}
}

Answer 1

Somewhere deep in resource processing code we have something like this:
try {
// Try loading some strings here.
} catch {
// Oops, could not load strings, try another way.
}
Exception is thrown and handled already, it would never show up in your application. The only way to see it is to attach debugger and observe this message.
As you could see from the code, it has nothing to do with your problem. The real problem here is what debugger shows you something you should not see.
Run the solution without debugging mode and it works fine.

Answer 2

This exception means that your program does not get Read access to the file from Windows.
Have you made sure that this file is not locked when your program tries to read it ?
For example, it could be a file that your own program is currently using.
If not, try to run your program as an Administrator and see if it makes a difference.