The type initializer for Oracle DataAccess Client OracleConnection threw an exception

Question

I have developed an application that uses Oracle Data Provider for  NET  I copy the application file   exe  and ODP library  Oracle DataAccess dll  on another computer that Oracle client and ODP NET are NOT installed on  When I run the application  I got the error msg  The type initializer for  Oracle DataAccess Client OracleConnection  threw an exception                    Exception Text                System TypeInitializationException  The type initlializer for  Oracle DataAccess Client OracleConnection at Oracle DataAccess Client OracleConnection  cctor     --- End of inner exception stack trace ---   at Oracle DataAccess Client OracleConnection  ctor String connectionString          Do I have to install ODP NET and Oracle client on the computer that I want to run my application  If yes  is there other way that I don t have to install them but still can run my application   Thank you

User · Answer

You need the oracle client driver installed for those classes to work.

There might be 3rd party connection frameworks out there that can handle Oracle, perhaps someone else might know of some specific ones.

User · Answer

Easiest Way      Right click on project and select  Manage NuGet Packages     Search for Oracle ManagedDataAccess  Install it    If you are using Entity Framework and your Visual Studio Version is 2012 or higher then   Again search for Oracle ManagedDataAccess EntityFramework  Install it  Use below name spaces in your  cs file  using Oracle ManagedDataAccess Client  using Oracle ManagedDataAccess EntityFramework    Its done  Now restart your visual studio and build your code  What do these packages do  After installing these packages no additional Oracle client software is required to be installed to connect to database

User · Answer

This is an old  but still relevant question  and while the answers here are helpful no one answer fully addressed both of the OP s questions   1  Do I have to install ODP NET and Oracle client on the computer that I want to run my application   YES - if you are using ODP NET  Unmanaged  This is the version that you typically install when you choose  Oracle Data Provider for  NET  in the Oracle Client installer  for example   You Download this from Oracle  just google it  Oracle URLs change often    But If you are using ODP NET  Managed  and you probably want to use this one this instead  then No  you only need to install  or deploy  ODP NET  Managed with the app  not the full Oracle Client  See below for details   2  If yes  is there other way that I don t have to install them but still can run my application   Yes  there is at least one way  And it is the Managed port of ODP NET   Unfortunately the usual workarounds  including ODBC  Microsoft s Oracle Provider for  NET  yes  that old  deprecated one   and the ODP NET  Unmanaged DLL all require the Oracle client to be installed  It wasn t until our friends at Oracle gave us a nice little   5MB  DLL that is also Managed  This means no more having to depoy 32-bit and 64-bit versions to go with 32-bit and 64-bit Oracle clients  And no more issues with assembly binding where you build against 10 0 2 1  or whatever  but your customers install a range of clients from 9i all the way to 12c  including the  g  ones in the middle  because you can just ship it with your app  and manage it via nuget   But if you use ODP NET  Managed which is available as a nuget package  then you do not need to install the Oracle Client  You only need the ODP NET  Managed DLL  And if you were previously using the ODP NET  Unmanaged DLL  it is very easy to switch  simply change all your references to the Managed ODP NET   csproj files in csharp  etc    and then change any using statements  for example  using Oracle DataAccess Client becomes using Oracle ManagedDataAccess Client and that s it   Unless you were supposedly using some of  the more advanced DB management features in the full client that are exposed in the ODP NET  Unmanaged  which I have not done myself  so good luck with that     And also nuke all of those annoying assemblyBindingRedirect nodes from your app config web config files and never sweat that junk again   References    ODP NET Details  http   www oracle com technetwork topics dotnet index-085163 html ODP NET is backward and foward-compatible  http   www oracle com technetwork topics dotnet multipledbs-089665 html Advanced Configuration  https   docs oracle com cd E48297 01 doc win 121 e41125 featConfig htm   Troubleshooting   That error typically means ODP NET was found OK  but Oracle client was not found or not installed  This could also occur when the architecture doesn t match  32-bit Oracle client is installed  but trying to use 64-bit Unmanaged ODP NET  or vice versa   This can also happen due to permissions issues and path issues and other problems with the app domain  your web app or your EXE or whatever  not being able to find the Oracle DLLs to actually communicate with Oracle over the network  the ODP NET Unmanaged DLLs are basically just wrappers for this that hook into ADO and stuff    Common solutions I have found to this problem   App is 64-bit     Install 64-bit Oracle Client  32-bit one wont work    App is 32-bit     Install 32-bit Oracle Client  64-bit one wont work    Oracle Client is already installed for the correct architecture     Verify your environment PATH and ORACLE HOME variables  make sure Oracle can be found  newer versions may use Registry instead  Verify the ORACLE HOME and settings in the Registry  And remember  Registry is either 32-bit or 64-bit  so make sure you check the one that matches your app   Verify permissions on the ORACLE HOME folder  If you don t know where this is  check the Registry  I have seen cases where ASP NET app worker process was using Network Service user and for some reason installing 32-bit and 64-bit clients side by side resulted in the permissions being removed from the first client for the Authorized Users group   fixing perms on the home folder fixed this  As always  it is handy to Use SysInternals Process Monitor to find out what file is missing or can t be read

User · Answer

Both Oracle Data Provider for  NET  from Oracle  and  NET Framework Data Provider for Oracle  from Microsoft  require Oracle Client installed on machine

User · Answer

Two options   Install Oracle client on the PC you want to run your program on  Use Oracle ManagedDataAccess dll   You can get it on NuGet  search  oracle managed   or download ODP NET Managed zip   link is to a beta version  but points you in the right direction  I use this so that the computers I deploy onto don t need Oracle client installed  N B  in my opinion this is good for console apps but annoying if you intend to install your application  so I install the client in that case

User · Answer

Ok  when you know for sure other applications that used the same process worked  on your new application make sure you have the data access reference and the three dll files     I downloaded ODAC1120320Xcopy 32bit this from the Oracle site   http   www oracle com technetwork database windows downloads utilsoft-087491 html  Reference  Oracle DataAccess dll  ODAC1120320Xcopy 32bit odp net4 odp net bin 4 Oracle DataAccess dll   Include these 3 files within your project    oci dll  ODAC1120320Xcopy 32bit instantclient 11 2 oci dll     oraociei11 dll  ODAC1120320Xcopy 32bit instantclient 11 2 oraociei11 dll  OraOps11w dll  ODAC1120320Xcopy 32bit odp net4 bin OraOps11w dll    When I tried to create another application with the correct reference and files I would receive that error message   The fix  Highlighted all three of the files and selected  Copy To Output    Copy if newer  I did copy if newer since one of the dll s is above 100MB and any updates I do will not copy those files again   I also ran into a registry error  this fixed it   public void updateRegistryForOracleNLS         RegistryKey oracle   Registry LocalMachine CreateSubKey   SOFTWARE ORACLE        oracle SetValue  NLS LANG    AMERICAN AMERICA WE8MSWIN1252        For the Oracle nls lang list  see this site  https   docs oracle com html B13804 02 gblsupp htm  After that  everything worked smooth   I hope it helps

User · Answer

You need an Oracle Client  http   www oracle com technology oramag oracle 08-nov o68odpnet html

[odp.net] The type initializer for 'Oracle.DataAccess.Client.OracleConnection' threw an exception

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