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IOException thrown from Image class or byte array

I'm extracting a ZIP file. This ZIP contains image files and an Excel file with a product list. When articles of different sizes are listed the article refers to the same image. I copy the image file to a local folder and write the (compressed) binary data to SQL server database.
So when it gets to the point where a JPG file shall be processed a second time, I get this exception, although I dispose the image object.
Worksheet ws;
string root = "C:\\images\\";
string file;
string importFolder = "C:\\import\\;
Dictionary <string, object> ins;
Image im;
Image th;
//Worksheet has been opened before
//ZIP has been extracted before to C:\import\
for (i = 2; i <= ws.Dimension.End.Row; i++) {
ins = new Dictionary<string, object>(); //Dictionary to write data to database
file = ws.Cells[i, 4].Text;
System.IO.File.Copy(importFolder + "\\" + file, root + "\\" + file, true); // <-- Here the exception is thrown in the second iteration
im = Image.FromFile(root + "\\" + file);
im = im.GetBetterThumbnail(1024);
byte[] im_data = im.GetJpgByteArray(85);
ins.Add("url", "www.test.de/images/" + file);
ins.Add("image_data", im_data);
ins.Add("image_size", im_data.Length);
//image will be written to database
im.Dispose();
im = null;
im_data = null;
//With these initializations there shouldn't be thrown an exception
} // end for
What am I missing? With resetting the Image object and byte array, there shouldn't be another reference to the image file.
I had a look on this
IOException: The process cannot access the file 'file path' because it is being used by another process
but I couldn't figure out, how to adept to my topic.
Yes, I could store all file names just to copy them once, but I think that's the lazy way.
Kind regards

You assign a value to the variable im two times.
One time you use im = Image.FromFile(root + "\\" + file) and the other time you use im = im.GetBetterThumbnail(1024). Could it be that this opens two handles that need to be closed?
Besides, it's better to use the using statement. Then you don't have to take care of the disposing by yourself.
For example like this:
for (i = 2; i <= ws.Dimension.End.Row; i++)
{
ins = new Dictionary<string, object>(); //Dictionary to write data to database
file = ws.Cells[i, 4].Text;
System.IO.File.Copy(importFolder + "\\" + file, root + "\\" + file, true);
using (im = Image.FromFile(root + "\\" + file))
{
// I guess that this method creates its own handle
// and therefore also needs to be disposed.
using (thumbnail = im.GetBetterThumbnail(1024))
{
byte[] im_data = thumbnail.GetJpgByteArray(85);
ins.Add("url", "www.test.de/images/" + file);
ins.Add("image_data", im_data);
ins.Add("image_size", im_data.Length);
//image will be written to database
}
}
} // end for

I got the issue solved by using a stream. The memory management works really better now.
New code:
//im = Image.FromFile(root + "\\" + file);
im = Image.FromStream(File.Open(root + "\\" + file, FileMode.Open));
So could it be that this is another 'Microsoft feature'?

Can't write to file c#

I have a loop which scans for xml files, when success it get in to loop and manipulate strings. Problem is i can't write post because i got warning file in use. How do i fix this?
Loop:
var dir = new DirectoryInfo(#"C:\Projektdata");
foreach (var file in dir.EnumerateFiles("*.xml", SearchOption.AllDirectories))
{
foreach (string line in File.ReadLines(file.DirectoryName + #"\" + file))
{
. . . .
Section to write file:
string directoryPath = file.DirectoryName + #"\" + file;
StreamWriter writer = new StreamWriter(directoryPath);
writer.WriteLine(source);
writer.Close();

Use it in a using directive:
using(var writer = new StreamWriter(directoryPath))
{
writer.WriteLine(source);
}
If the error still occurs, try to save the string into a variable, and use this writing process outside of the scope of the foreach iterations. (Since the foreach iteration reads the file line by line, so it means the file is open.)

You can't write to an open file. You already opened the same file for reading.
File.ReadLines(file.DirectoryName + #"\" + file);
and
string directoryPath = file.DirectoryName + #"\" + file;
StreamWriter writer = new StreamWriter(directoryPath);
File.ReadLines() is returning an IEnumerable<string> and will yield each line. So within the loop, the file is still open. Assumed that the writing is within the loop.

i have to Create Folder in bin-debug and then create and write in text file in it

i wrote this code , it ctreates folder named "Fitness50" each time but the text file is not created.i want to create textfile within this folder and then save values of an arraylist.
so for i have tried this
DirectoryInfo myDir = new DirectoryInfo(#"E:");
ParentFolderName1 = "Fittness50";
myDir.CreateSubdirectory(ParentFolderName1);
myDir = new DirectoryInfo(ParentFolderName1);
ParentFolderName1 = "Fittness50";
myDir.CreateSubdirectory(ParentFolderName1);
FileName1 = "./" + "" + ParentFolderName1 + "" + "/" + "Fittness10" + "" + "" + PopulationID + "" + ".txt";
FileStream fs2 = new FileStream(FileName1, FileMode.Create, FileAccess.Write);
StreamWriter SW2 = new StreamWriter(fs2);
for (i = 0; i < AlTargetData.Count; i++)
{
SW2.WriteLine(AlTargetData[i]);
}
AlTargetData.Clear();
SW2.Close();
fs2.Close();

Well, first of all, / is not the preferred directory separator on Windows, but \ is. Just because / happens to work, there's no reason to use it. Secondly, you're not creating the Fittness10 folder at all, but you're creating Fittness50 twice. And third, you're not writing the file to the folders you create, but to the current working directory ..
Your code (or at least what I understand you want to achieve) can be shortened significantly to this:
string path = #"E:\Fittness50\Fittness10";
if (!Directory.Exists(path))
Directory.CreateDirectory(path);
string fileName = Path.Combine(path, String.Format("{0}.txt", PopulationID));
File.WriteAllText(fileName, String.Join(Environment.NewLine, AlTargetData));
Please note that you should not consider writing to bin\debug. There will be no bin\debug on the end-user's machine. If the user installs your application, it will be most probably be installed in the Program Files folder, which your application won't be allowed to write to. Instead, consider writing to a common location, like the ones you can chose from in Environment.GetFolderPath.

File Watcher error

My file watcher event read the first file only and then I get the following error:
"Error: System.IO.IOException: The process cannot access the file 'D:\TREE\Dump\TF20141004011343313.txt' because it is being used by another process."
Here is my code:
int? msgID;
string dup ="";
try
{
//---------read from file------------
string block;
using (StreamReader sr = File.OpenText(MsgsPath + "\\" + e.Name))
{
block = sr.ReadToEnd();
}
and "using" should handle the open and close automatically, right?
I then use this code to move processed files:
File.Move(MsgsPath + "\\" + e.Name, MsgsPath + "\\Archive\\" + e.Name);

The FileSystemWatcher Created event is triggered as soon as the other process opens the file for writing. Following that, one or more Changed events will follow, when other process writes to the file, and finally closes it.
The easiest way to get around the error, would be to wait a short while before trying to access the file:
Thread.Sleep(500);
A more advanced method, is to wait a short while from the last Changed event.

Append to file failure when executable not in same folder as data files

Problem is now solved. Mistake by me that I hadn't seen before.
I am pretty new to coding in general and am very new to C# so I am probably missing something simple. I wrote a program to pull data from a login website and save that data to files on the local hard drive. The data is power and energy data for solar modules and each module has its own file. On my main workstation I am running Windows Vista and the program works just fine. When I run the program on the machine running Server 2003, instead of the new data being appended to the files, it just overwrites the data originally in the file.
The data I am downloading is csv format text over a span of 7 days at a time. I run the program once a day to pull the new day's data and append it to the local file. Every time I run the program, the local file is a copy of the newly downloaded data with none of the old data. Since the data on the web site is only updated once a day, I have been testing by removing the last day's data in the local file and/or the first day's data in the local file. Any time I change the file and run the program, the file contains the downloaded data and nothing else.
I just tried something new to test why it wasn't working and think I have found the source of the error. When I ran on my local machine, the "filePath" variable was set to "". On the server and now on my local machine I have changed the "filePath" to #"C:\Solar Yard Data\" and on both machines it catches the file not found exception and creates a new file in the same directory which overwrites the original. Anyone have an idea as to why this happens?
The code is the section that download's each data set and appends any new data to the local file.
int i = 0;
string filePath = "C:/Solar Yard Data/";
string[] filenamesPower = new string[]
{
"inverter121201321745_power",
"inverter121201325108_power",
"inverter121201326383_power",
"inverter121201326218_power",
"inverter121201323111_power",
"inverter121201324916_power",
"inverter121201326328_power",
"inverter121201326031_power",
"inverter121201325003_power",
"inverter121201326714_power",
"inverter121201326351_power",
"inverter121201323205_power",
"inverter121201325349_power",
"inverter121201324856_power",
"inverter121201325047_power",
"inverter121201324954_power",
};
// download and save every module's power data
foreach (string url in modulesPower)
{
// create web request and download data
HttpWebRequest req_csv = (HttpWebRequest)HttpWebRequest.Create(String.Format(url, auth_token));
req_csv.CookieContainer = cookie_container;
HttpWebResponse res_csv = (HttpWebResponse)req_csv.GetResponse();
// save the data to files
using (StreamReader sr = new StreamReader(res_csv.GetResponseStream()))
{
string response = sr.ReadToEnd();
string fileName = filenamesPower[i] + ".csv";
// save the new data to file
try
{
int startIndex = 0; // start index for substring to append to file
int searchResultIndex = 0; // index returned when searching downloaded data for last entry of data on file
string lastEntry; // will hold the last entry in the current data
//open existing file and find last entry
using (StreamReader sr2 = new StreamReader(fileName))
{
//get last line of existing data
string fileContents = sr2.ReadToEnd();
string nl = System.Environment.NewLine; // newline string
int nllen = nl.Length; // length of a newline
if (fileContents.LastIndexOf(nl) == fileContents.Length - nllen)
{
lastEntry = fileContents.Substring(0, fileContents.Length - nllen).Substring(fileContents.Substring(0, fileContents.Length - nllen).LastIndexOf(nl) + nllen);
}
else
{
lastEntry = fileContents.Substring(fileContents.LastIndexOf(nl) + 2);
}
// search the new data for the last existing line
searchResultIndex = response.LastIndexOf(lastEntry);
}
// if the downloaded data contains the last record on file, append the new data
if (searchResultIndex != -1)
{
startIndex = searchResultIndex + lastEntry.Length;
File.AppendAllText(filePath + fileName, response.Substring(startIndex+1));
}
// else append all the data
else
{
Console.WriteLine("The last entry of the existing data was not found\nin the downloaded data. Appending all data.");
File.AppendAllText(filePath + fileName, response.Substring(109)); // the 109 index removes the file header from the new data
}
}
// if there is no file for this module, create the first one
catch (FileNotFoundException e)
{
// write data to file
Console.WriteLine("File does not exist, creating new data file.");
File.WriteAllText(filePath + fileName, response);
//Debug.WriteLine(response);
}
}
Console.WriteLine("Power file " + (i + 1) + " finished.");
//Debug.WriteLine("File " + (i + 1) + " finished.");
i++;
}
Console.WriteLine("\nPower data finished!\n");

Couple of suggestions wich I think will probably resolve the issue
First change your filePath string
string filePath = #"C:\Solar Yard Data\";
create a string with the full path
String fullFilePath = filePath + fileName;
then check to see if it exists and create it if it doesnt
if (!File.Exists(fullFilePath ))
File.Create(fullFilePath );
put the full path to the file in your streamReader
using (StreamReader sr2 = new StreamReader(fullFilePath))