Could not load file or assembly dll or one of its dependencies

Question

I have this dll that I created a long time ago and use to connect to the db of a specific software that I develop for  I have had no issues for well over 4 years and countless applications with this dll   Trying to deploy my latest creation  I get the following error    System IO FileNotFoundException  Could not load file or assembly      dll  or one of its dependencies  The specified module could not be found    So  for every dll I ever wrote  I always made a simple forms application to test that dll just by itself  Running that simple app yielded the same error  The dll doesn t load or use anything else than  System  System Data  System XML  So as far as depencies of it go  I don t see anything wrong   By the way everything works on a dev station  The problem is limited to deployment stations   Net and the necessary redistributables  since I do everything in C    are deployed and working   Running FUSLOGVW exe showed everything as working fine   Running depends exe said  Warning  At least one module has an unresolved import due to a missing export function in a delay-load dependent module   I already tried rewriting the whole thing  Which yielded the same results   Clues anyone   EDITS  Here is the total error message   See the end of this message for details on invoking    just-in-time  JIT  debugging instead of this dialog box                    Exception Text                  System IO FileNotFoundException  Could not load file or assembly  connectionTo dll  or one of its dependencies  The specified module could not be found    File name   connectionToJobboss32 dll       at TESTConnection Form1 button1 Click Object sender  EventArgs e       at System Windows Forms Control OnClick EventArgs e       at System Windows Forms Button OnClick EventArgs e       at System Windows Forms Button OnMouseUp MouseEventArgs mevent       at System Windows Forms Control WmMouseUp Message amp  m  MouseButtons button  Int32 clicks       at System Windows Forms Control WndProc Message amp  m       at System Windows Forms ButtonBase WndProc Message amp  m       at System Windows Forms Button WndProc Message amp  m       at System Windows Forms Control ControlNativeWindow OnMessage Message amp  m       at System Windows Forms Control ControlNativeWindow WndProc Message amp  m       at System Windows Forms NativeWindow Callback IntPtr hWnd  Int32 msg  IntPtr wparam  IntPtr lparam                         Loaded Assemblies                  mscorlib       Assembly Version  4 0 0 0       Win32 Version  4 0 30319 1  RTMRel 030319-0100        CodeBase  file    C  Windows Microsoft NET Framework v4 0 30319 mscorlib dll   ----------------------------------------   TESTConnection       Assembly Version  1 0 3996 18980       Win32 Version         CodeBase  file    C  Program 20Files 20 x86  conn TESTConnection exe   ----------------------------------------   System Windows Forms       Assembly Version  4 0 0 0       Win32 Version  4 0 30319 1 built by  RTMRel       CodeBase  file    C  Windows Microsoft Net assembly GAC MSIL System Windows Forms v4 0 4 0 0 0  b77a5c561934e089 System Windows Forms dll   ----------------------------------------   System Drawing       Assembly Version  4 0 0 0       Win32 Version  4 0 30319 1 built by  RTMRel       CodeBase  file    C  Windows Microsoft Net assembly GAC MSIL System Drawing v4 0 4 0 0 0  b03f5f7f11d50a3a System Drawing dll   ----------------------------------------   System       Assembly Version  4 0 0 0       Win32 Version  4 0 30319 1 built by  RTMRel       CodeBase  file    C  Windows Microsoft Net assembly GAC MSIL System v4 0 4 0 0 0  b77a5c561934e089 System dll   ----------------------------------------     There is no errors in the event viewer

User · Answer

1  Copy DLLs from  Externals ffmpeg bin  to your project s output directory  where executable stays   2  Make sure your project is built for x86 target  runs in 32-bit mode    Follow this thread for more

User · Answer

I had the same issue with a dll yesterday and all it referenced was System  System Data  and System Xml   Turns out the build configuration for the Platform type didn t line up   The dll was build for x86 and the program using it was  Any CPU  and since I am running a x64 machine  it ran the program as x64 and had issues with the x86 dll   I don t know if this is your issue or not  just thought that I would mention it as something else to check

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I recently hit this issue  the app would run fine on the developer machines and select others machines but not on recently installed machines  It turned out that the machines it did work on had the Visual C   11 Runtime installed while the freshly installed machines didn t  Adding the Visual C   11 Runtime redistributable to the app installer fixed the issue

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Had the same issue and got it resolved by making sure projects in the solution have the same configuration and platform  in my case it was Debug x64   Somehow the VIsual Studio was missing x64 for part of the projects and I edited the  sln file manually  copied the configurations and platforms from correctly built projects to the projects that were missing the settings I needed   This is what it looks like for one of the projects    1BA29980-EE5D-4476-AFFC-0F177B6C9865  Debug Any CPU ActiveCfg   Debug Any CPU  1BA29980-EE5D-4476-AFFC-0F177B6C9865  Debug Any CPU Build 0   Debug Any CPU  1BA29980-EE5D-4476-AFFC-0F177B6C9865  Debug x64 ActiveCfg   Debug x64  1BA29980-EE5D-4476-AFFC-0F177B6C9865  Debug x64 Build 0   Debug x64  1BA29980-EE5D-4476-AFFC-0F177B6C9865  Release Any CPU ActiveCfg   Release Any CPU  1BA29980-EE5D-4476-AFFC-0F177B6C9865  Release Any CPU Build 0   Release Any CPU  1BA29980-EE5D-4476-AFFC-0F177B6C9865  Release x64 ActiveCfg   Release x64  1BA29980-EE5D-4476-AFFC-0F177B6C9865  Release x64 Build 0   Release x64   But then the same error occurred for a project that had a Java file    jar  in the dependencies  I had to edit Environment Variables manually to create a record with this value     C  Program Files Java jre1 8 0 171 bin server   for Java s path  and put it on top of the Path items   This fixed the issue until I updated Java on my machine  I had to edit the version number in Environment Variables to match the updated folder name      C  Program Files Java jre1 8 0 181 bin server

User · Answer

I had the same issue - a  dll working all the time  then my computer crashed and afterwards I had this problem of  could not load file or assembly     dll   Two possible solutions  when the computer crashed there may be some inconsistent files in  C  Users  lt yourUserName gt  AppData Local Temp Temporary ASP NET Files   Deleting that folder  recompiling and the error was gone   Once I had also to delete my packages folder  I had read that somewhere else   Allow Visual Studio   nuget to install missing packages  or manually reinstall  and afterwards everything was fine again

User · Answer

I had the same problem  For me  it was caused by the default settings in the local IIS server on my machine  So the easy way to fix it  was to use the built in Visual Studio development server instead     Newer IIS versions on x64 machines have a setting that doesn t allow 32 bit applications to run by default  To enable 32 bit applications in the local IIS  select the relevant application pool in IIS manager  click  Advanced settings   and change  Enable 32-Bit Applications  from False to True

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This answer is totally unrelated to the OP s situation  and is a very unlikely scenario for anyone else too  but just in case it may help someone      In my case I was getting  Could not load file or assembly  System Windows Forms  Version 4 0 0 0      because I had disassembled and reassembled the program using ILDAsm exe and ILAsm exe from  Net Framework   SDK version 2  Switching to ILDAsm exe and ILAsm exe from  Net Framework   SDK version 4 fixed the problem     Strangely  even though doing what I did may seem like an obvious error  the resulting EXE file that didn t work did indicate that it targeted  Net 4 when examined with JetBrains dotPeek

User · Answer

or one of its dependencies   That s the usual problem  you cannot see a missing unmanaged DLL with Fuslogvw exe   Best thing to do is to run SysInternals  ProcMon utility   You ll see it searching for the DLL and not find it   Profile mode in Dependency Walker can show it too

User · Answer

I ran into this recently   It turned out that the old DLL was compiled with a previous version  Visual Studio 2008  and was referencing that version of the dynamic runtime libraries   I was trying to run it on a system that only had  NET 4 0 on it and I d never installed any dynamic runtime libraries   The solution   I recompiled the DLL to link the static runtime libraries   Check your application error log in Event Viewer  EVENTVWR EXE    It will give you more information on the error and will probably point you at the real cause of the problem

User · Answer

An easier way to determine what dependencies a native DLL has is to use Dependency Walker - http   www dependencywalker com   I analysed the native DLL and discovered that it depended on MSVCR120 DLL and MSVCP120 DLL  both of which were not installed on my staging server in the System32 directory  I installed the C   runtime on my staging server and the issue was resolved

[.net] Could not load file or assembly '***.dll' or one of its dependencies

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