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.NET Forum / .NET Framework / Interop / July 2004PRB with accessing Ms Access from .NET
Hi We have old application which was wrotten in VB6, it has Access type library referenced in Project_Name.vbp : Reference=*\G{4AFFC9A0-5F99-101B-AF4E-00AA003F0F07}#8.0#0#..\..\Program Files\Microsoft Office\Office\MSACC8.OLB#Microsoft Access 8.0 Object Library this application works fine on Access ver 2000 and on Access 2003 with .mdb with certificates currently we want to port that app from VB6 to VB.NET, on my machine, where i have Office XP installed everything works fine, when i move .exe to machine where Office 2000 is installed, it returns with error 'Object reference not set to an instance of object' on line : accessobj.OpenCurrentDatabase() we use RCW created by VS.NET accessobj is created successfully with New Access.Application , here is some code : accessobj = New Access.Application 'No error '... accessobj.DBEngine.CompactDatabase("..", "...") 'No error '... accessobj.OpenCurrentDatabase("..") 'Error Here !!! in metadata of Interop.Access.dll created by VS.NET there is the same CLSID referenced as in old VB6 project. is this error caused by different version of Access installed on that machine .. or maybe i'm doing something wrong .. ? we want this app to be working with possibly any version of Access (a least any >= 2000). is there any simple way to accomplish this ? any help appreciated regards, Konrad Can't see the rest of your code in that example, but 'Object reference not set to an instance of object' means that an object (such as accessobj) is null.  SignaturePhil Wilson [MVP Windows Installer] > Hi > [quoted text clipped - 37 lines] > > regards, Konrad > Can't see the rest of your code in that example, but 'Object reference not > set to an instance of object' means that an object (such as accessobj) is > null. thats not the case here, i checked against this case and it for sure is not null the problem here was that OpenCurrentDatabase function has changed between version 9.0 and 10.0 of Access COM object (actually the header has changed, its enough), and thats why it returned Null Pointer Exception i've solved this problem by compiling application with ver 9.0 of Access COM installed on system (and Interop.Access.dll was generated on this system too), ver 10.0 seems backward compatible with 9.0, at least with regard to methods i need. For example .Version member is not implemented in ver 9.0 Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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