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I am trying to access Microsoft word instance through my service but I am getting this error
Operation unavailable (Exception from HRESULT: 0x800401E3 (MK_E_UNAVAILABLE)) ,
I have opened word document ( i can also see WINWORD.EXE in Task Manager) ,
I am using VS 2010 and MS Office 2003. Here is my code

Dim fs As New FileStream("D:\log.txt", FileMode.OpenOrCreate, FileAccess.Write)
        Dim sw As New StreamWriter(fs)
        sw.BaseStream.Seek(0, SeekOrigin.End)
        Dim wordapp As Word.Application
        wordapp = Marshal.GetActiveObject("Word.Application")
        For Each doc As Word.Document In wordapp.Documents
            sw.WriteLine(doc.FullName.ToString() + "\n" +

if i use this code in windows form application it works perfect, but doesn’t works in windows service.Why is that for ? Windows Service Doesn’t support Microsoft.Office.Interop ? If it does work please guide.
Updated 18-Apr-18 20:47pm
ArunAmalraj 22-Feb-13 6:07am
Hello muneebalikiyani,

Check for User Rights.

It will not work if...Your application is running as administrator and WINWORD with normal user rights.
muneebalikiyani 22-Feb-13 6:24am
thanks , but what can i do to make it work
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Solution 1

Run your service with your credentials - otherwise it won't be able to access Word running with your credentials.
fjdiewornncalwe 22-Feb-13 9:37am
My 5.
muneebalikiyani 26-Feb-13 23:19pm
I have done that also , i think Marshall.getactiveobject() doesn't works for windows services, please correct me if i am wrong
Member 11615348 15-Apr-16 3:14am
Even I am getting the same error:
Operation unavailable (Exception from HRESULT: 0x800401E3 (MK_E_UNAVAILABLE))

I am using VS 2015. Can anybody help on this?
pawan2261872 25-Jan-18 5:03am
Your visual syudio might be running in administrator mode.
Both visual studio and the fetching application(word) should be in same mode.
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Solution 2

Add reference only of "Microsoft.Office.Interop.Excel.dll"
 //This requires excel app (excel.exe*32) to be running means any excel sheet should be open. If excel not running then it will throw error.
            excelApp = (Excel.Application)Marshal.GetActiveObject("Excel.Application");
            excelApp.Visible = false;
            //create new excel instance
            excelApp = new Excel.Application();
            excelApp.Visible = false;
This worked for me.
Advantage: No need to copy Microsoft.Office.Interop.Excel.dll to your installed foler. Since MS excel is installed it will take from GAC.

I used Office.dll too but not sure if its really required.
Richard MacCutchan 19-Apr-18 4:06am
The question is about using MSWord, not Excel. It was also answered five years ago.

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