Error Metadata file Release project dll could not be found in Visual Studio

Question

Recently I started to get this message randomly      Metadata file      Release project dll  could not be found in Visual Studio   I have a solution with several projects in it  The current build mode is Debug and all projects  configurations are set to Debug  But when I try to run the main project - sometimes it gives me a few errors  all of which are  Metadata file      Release projectX dll  could not be found  - and  look  it says about RELEASE folder  though current mode is Debug  Why  I tried to search for reference to  Release projectX dll  inside all solution files  and I found one in ResolveAssemblyReference cache file   I made a good search over the Internet and found a few people with a similar problem  but there was no solution  or at least no working solution   I tried to delete references to those projects and read them  but in some time I start getting these errors again   It seems like a bug  Why does it search for referenced projects in Release folders when I always use Debug mode   PS  For those who met this problem  I couldn t solve it in an easy way  It disappeared only after I reinstalled Windows

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I had this problem and it was due to an invalid method in the offending library (dll) that did not return a value, e.g.

public bool DoSomething()
{
   //I never bothered putting code here....

}

When I commmented this out everything compiled :)

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I had a similar problem  I removed classes and an interface and after this my builds started to fail    remove all builds so that no project builds  configuration manager  check the build order  take a screenshot and put it in Paint  D  enable one by one and do each time Clean  amp  Rebuild and build  Now you know the project that failed   -    In my situation I had a Folder with one interface inside  e g  FooSolution StupidProject Interfaces What happened is that I commented out the interface IUnicorns  FooSolution StupidProject Interfaces IUnicorns   so that it would not be used anymore  No other project had IUnicorn in use anymore  Everything was fine   However     some other projects were still having using statements to that folder   using FooSolution StupidProject Interfaces   Solution    Instead of commenting the interface like     public interface IUnicorn     I commented also the namespace above the interface  like this      namespace FooSolution StupidProject Interfaces          public interface IUnicorn      I searched my other projects and made sure there was no using anymore to that namespace  Clean and rebuild and a good coffee  -    Conclusion   check your usings in other projects

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I was having this issue when trying to add a project reference  and after a lot of searching and trying many of the things above  my build configuration and outputs were correct  I finally just deleted the  bin and  obj folders from the source and referencing project  Honestly I believe it was the obj folder not containing the correct metadata or corrupted metadata  All is fixed now  This was with Visual Studio 2015 -  NET 4 6 projects  UPDATE  The above worked on the first build  but on subsequent builds it failed  so I ended up recreating the solution file  and removing and reading the NuGet packages that were referenced incorrectly in my project files which pointed to the incorrect hint path  That seemed to have fixed it thus far on subsequent builds  A sample reference within a  csproj file  lt ItemGroup gt       lt Reference Include  quot Antlr3 Runtime  Version 3 5 0 2  Culture neutral  PublicKeyToken eb42632606e9261f  processorArchitecture MSIL quot  gt     lt SpecificVersion gt False lt  SpecificVersion gt     lt HintPath gt       packages Antlr 3 5 0 2 lib Antlr3 Runtime dll lt  HintPath gt       lt  Reference gt   lt  ItemGroup gt

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Are you using a database code generation tool like SQLMETAL in your project   If so  you may be facing a pluralized to unpluralized transition issue   In my case  I have noted that some old pluralized     table names  upon which SQLMETAL adds  by default  an  s  letter at the end  table references to classes generated by SQLMETAL   Since  I have recently disabled Pluralization of names  after regerating some database related classes  some of them lost their  s  prefix  Therefore  all references to affected table classes became invalid  For this reason  I have several compilation errors like the following       xxxx  does not contain a definition for  TableNames  and no extension method  TableNames  accepting a first argument of type  yyyy  could be found  are you missing a using directive or an assembly reference     As you know  I takes only on error to prevent an assembly from compiling  And that is the missing assemply is linkable to dependent assemblies  causing the original  Metadata file  XYZ  could not be found   After fixing affected class tables references manually to their current names  unpluralized   I was finnaly able to get my project back to life       If option  Visual Studio   Tools menu   Options   Database Tools   O R Designer   Pluralization of names is enabled  some SQLMETALl code generator will add an  s  letter at the end of some generated table classes  although table has no  s  suffix on target database  For further information  please refer to http   msdn microsoft com en-us library bb386987 v vs 110  aspx  This post has lots of good advices  Just added one more

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For me this was caused by the Build target having been rewritten to not output the dll  Removing this to fall back on the default Build target fixed the issue

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same happened to me today as described by Vidar    I have a Build error in a Helper Library  which is referenced by other projects  and instead of telling me that there s an error in Helper Library  the compiler comes up with list of MetaFile-not-found type errors  After correcting the Build error in Helper Library  the MetaFile errors gone   Is there any setting in VS to improve this

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We recently ran into this issue after upgrading to Office 2010 from Office 2007 - we had to manually change references in our project to version 14 of the Office Interops we use in some projects   Hope that helps - took us a few days to figure it out

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I ended up deleting my references  I had added them properly using the projects tab  and they used to build just fine   hand editing my  csproj files and removing bizarre entries that didn t belong -- and setting my outputs for debug and release  x86 and x64 and any cpu to all be   bin  -- I built it once  then re-added the reference  again  using the projects tab   and everything started working again for me   Didn t have to restart Visual Studio at all

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In my case  I had some errors in my code  Visual Studio showed the error you had instead of the actual errors  like syntax errors or unknown class names  Try cleaning the solution and building project after project  This way you will discover the actual errors   Again  this is just what cause the error for me

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We have that problem quite often  but only with references to C   CLI projects from C  projects  It s obviously a bug deep down in Visual Studio that Microsoft decided not to fix  because it s  too complex  and they promised an overhaul of the C   build system which is now targeted for Visual nbsp Studio nbsp 2010   That was some time ago  and maybe the fix even went into Visual nbsp Studio nbsp 2008  I didn t follow up on it any more  However  our typical workaround was   Switch configuration Restart Visual Studio Build the solution

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Well  my answer is not just the summary of all the solutions  but it offers more than that    Section  1    In general solutions   I had 4 errors of this kind     metadata file could not be found     along with 1 error saying  Source File Could Not Be Opened     Unspecified error         I tried to get rid of    metadata file could not be found    error  For that  I read many posts  blogs etc and found these solutions may be effective  summarizing them over here     Restart VS and try building again  Go to  Solution Explorer   Right click on Solution  Go to Properties  Go to  Configuration Manager   Check if the checkboxes under  Build  are checked or not  If any or all of them are unchecked  then check them and try building again  If the above solution s  do not work  then follow sequence mentioned in step 2 above  and even if all the checkboxes are checked  uncheck them  check again and try to build again  Build Order and Project Dependencies   Go to  Solution Explorer   Right click on Solution  Go to  Project Dependencies      You will see 2 tabs   Dependencies  and  Build Order   This build order is the one in which solution builds  Check the project dependencies and the build order to verify if some project  say  project1   which is dependent on other  say  project2   is trying to build before that one  project2   This might be the cause for the error   Check the path of the missing  dll   Check the path of the missing  dll  If the path contains space or any other invalid path character  remove it and try building again   If this is the cause  then adjust the build order      Section  2    My particular case   I tried all the steps above with various permutations and combinations with restarting VS few times  But  it did not help me    So  I decided to get rid of other error I was coming across   Source File Could Not Be Opened     Unspecified error           I came across a blog   http   www anujvarma com tfs-errorsource-file-could-not-be-opened-unspecified-error  comment-1539   I tried the steps mentioned in that blog and I got rid of the error  Source File Could Not Be Opened     Unspecified error       and surprisingly I got rid of other errors     metadata file could not be found     as well     Section  3    Moral of the story   Try all solutions as mentioned in section  1  above  and any other solutions  for getting rid of the error  If nothing works out  as per the blog mentioned in section  2  above  delete the entries of all source files which are no longer present in the source control and the file system from your  csproj file

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For me was to remove delete entire  vs folder that is an invisible one  and then   - Build - Rebuild    and done

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The  30th answer  -   In VS2015    Right-click on Solution Select Project Build Order Look at the list of projects in Project Build Order Build each of your projects in that order Inspect the Output   In my case  doing it step-by-step helped discovered what my problem is without all those errors thrown left and right    If you had to know  I added Entity Framework  EF  6 1 3 via NuGet when the project was set for  NET 4 5 2  I later downgraded the  NET Framework down to 4  and then the error was more obvious  Via NuGet  I uninstalled EF and re-added it

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I had the same problem  I noticed that my db context  EF4  that was located in the project dll wasn t recognize for some reason  I deleted it and created another one instead  and that solved it for me

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I had the exact same problem  Big visual studio solution with 50  projects   All references were added as projects   Project build order was correct  right click on project and select build order     However when building some of the higher level projects the  root  project they depended on were not built   The problem was that these projects were not selected to build under the current configuration  don t know how this happened     To check this select  Configuration Manager   Build menu  e check if the problematic projects are set to build

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It seems to happen when you checkout a solution with multiple projects that have references between them  and you haven t built it before  If you have references directly to the dlls  instead of referencing the project  you ll get this message  You should always use the Projects tab in the Add Reference dialog to add a reference to a project in the same solution  This way  VS can know the correct order in which to build the solution

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I had the same issue  non of the provided answers fixed it before  Apparently this could be a problem with the  csproj file  For some reason the references to files that were not even made anywhere in my code were still  missing      Open your  csproj file with a text editor and look for the files missing  delete  save and be happy

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Did you check the Configuration manager settings  In the project settings dialog top right corner   Sometimes it happens that between all the release entries a debug entry comes in  If so  the auto dependency created by the dependency graph of the solution gets all confused

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In VS 2015  removing  Analyzers  under  References  solved the issue

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Re-open Visual Studio as Administrator

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I had the same problem myself   Visual Studio 2013 only told me that it couldn t reference to it  and it couldn t find the metadata  When I opened my solution  which has multiple projects in it  it said that I was using projects lower than the framework version of one of my projects   So I switched everything to version 4 5  and it worked again

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CHECK YOUR PROJECT PATH  It should have no irregular character like comma and space  for example this is incorrect path  d  my applications Project1  and this is true path d  my applications Project1  The visual studio cannot build the project when there is a non alphabetic and numeric character in its path in disk and it show no message for this fault   Also some installation tools have same problem when they start installation and can not be extracted

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In my case it was caused by two things  VS 2012    1  One of the projects was configured for AnyCPU instead of x86  2  A project that was referenced had somehow the  Build  checkbox unchecked   Do check your Build   Configuration Manager to get an overview of what is being built and for which platform  Also make sure you check it for both Debug  amp  Release as they may have different settings

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I find that this usually occurs to me when i still have a method declaration in an interface  which a class implements  but that i had later removed and had forgotten to remove it from the interface as well  I usually just save the entire solution every 30mins n then just revert back to an earlier version if i cant find the error

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I had the same issue and the reason behind this issue is that the dll file of reference project is being used by some other process  In my case  I was debugging an application and application was attached with visual studio debugger  When I was re-building another application which is using same project  then I was getting this error  After de-attaching  I was able to build second application successfully

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In my case  during a merge  it seems the solution file was missing some project references  Manually re-adding the project to the solution fixed it  You can also manually edit the solution file but you need to be careful and know what you are doing

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Had the same problem today   My application  a Windows Forms applications  accidently had a reference to itself  Weird   Once removed  the error went away   The reference got added each time I dragged a user control  located in the Windows Forms project itself  to a form

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Check wether the  vs folder in the project root is hidden or not  Mine wasn t  and it should  since I did a copy paste from another pc  Deleting it solved the problem  Visual Studio 2015 just recreated it for me

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Everyone is correct   try everything    in order of a little to a lot of time wasted    Do you have bad code  Fix that first  Clean Solution  amp  Restart Visual Studio Remove   Add References Check your build order w  larger projects and verify Manually rebuild sub-projects Manually copy dlls between projects into associated bin folders Go get some coffee  play some pinball and come back tomorrow   you may think of something else in the meanwhile

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Most of the answares say that you need to remove the libraries of your solution  this is true but when you re-add the libraries the error will be shown again  You need to verify if all the libraries referenced have a compatible  net framework with the  net framework of your solution  Then fix all the errors in your code and rebuild the solution

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I had this problem and took long while to figure it out  Problem came up when I removed projects from solution and replaced those with nuget packages    Solution seemed to be fine but the  csproj file still contained those projects multiple times as reference   Seems that VS does not clean that file appropriately  It was still referencing the removed projects under the hood  When manually removed  the references from csproj file all works again  wohoo

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I seem to recall having a similar problem a few months ago   I solved it temporarily by copying the referenced DLL to the Release folder  thus satisfying Visual Studio s expectations   Later  I discovered the reference to the Release DLL in my actual code   You should try doing a search through the entire project for  release project dll     Also  I have noticed that Visual Studio unit test projects sometimes put a  DeploymentItem  attribute on each of the test methods pointing to your target DLL  and if you switch between Debug and Release  Visual Studio can get confused if the DLL is no longer in the expected location   In my experience  these attributes can be safely deleted if you didn t put them there yourself as part of a  single deployment  scenario

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I had the same problem  Manually removing and adding the dlls did not help  ClassLibraries did not compile for all the projects and were missing in the     bin Debug folder for the project  because I cleaned solution by mistake   Since the class library did not compile that means there may be some errors somewhere in one of those sub projects   Solution  Since my dlls were there for the     bin Release folder  I tried to rebuild on Release mode and found an error on one line in one of the sub projects  Solving the error and rebuilding the solution got rid off the build error

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Sometimes VS2010 switches my configuration from Any CPU to Mixed Platforms  When this happens I get this error message    To resolve it I switch back to Any CPU  1  Right click on the solution and select properties  2  Click on Configuration Properties and then the Configuration Manager    button  3  Under Active solution platform select Any CPU

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This issue has been resolved  I opened up the Package Manager Settings and clicked  Allow NuGet to download missing packages   The project now builds   https   github com gitextensions gitextensions issues 1969

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I also had this problem today  Mine was caused by a cyclic dependency  Project A referenced Project B and vice versa

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For me Visual Studio had created a projectname v11  of type  Visual Studio Solution User Options    I deleted this file and restarted and everything was fine

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I ve had this problem before and the only way I ve found to solve it is to run Clean Solution and then restart Visual Studio

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in my case i was working on a branch off master  so i checked out master branch  ran a build and then checked out my branch  It fixed the issue  If you already are on master  i suggest you check out previous commit and then build it

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When you say you deleted references to those projects and re-added them  how did you re-add them  exactly   Did you use the  Browse  tab in the  Add Reference  dialog in Visual Studio   Or  did you use the  Projects  tab  which lists neighboring projects in your solution    Edit   If you use the  Browse  tab  and manually add the reference to your  dll that is located in the  Release folder  then Visual Studio will always look for the  dll in that location  regardless of what mode you re currently in  Debug or Release    If you removed the actual  dll file from the Release folder  either manually or by doing  Clean Solution    then your reference will break because the  dll does not exist   I d suggest removing the reference to ProjectX dll  and add it in again--but this time  use the  Projects  tab in the  Add Reference  dialog   When you add a reference this way  Visual Studio knows where to get the appropriate  dll   If you re in Debug mode  it will get it from the  Debug folder   If in Release mode  the  Release folder   Your build error should go away  and you also will no longer be  improperly  referencing a Release  dll while in Debug mode

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For me  I was using EntityFramework 6 2 0 Updated to EntityFramework 6 4 0 then problem is solved

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This problem is due to pdb files or CodeContracts   To resolve it    Clean your output folder and rebuild the solution  Re-Configure the CodeContracts or disable it for temporary build

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For me it s usually the target framework being off  4 5 2 instead of 4 6  If you fix the target framework of the project to match the target framework of the solution and build  a new  dll will be created

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I ve also seen this error in solutions where I have multiple projects  usually netTiers projects where I ve updated one or more of the sub-projects to target the 4 0 framework    It can be problematic to remove   Oftentimes it can be resolved  however  by first fixing all other errors in sub-projects  eg  any missing references   individually rebuilding those sub-projects  then removing adding back any references to those sub-projects in Visual Studio   Personally  I ve had little luck resolving this error by cleaning the solution alone

[visual-studio] Error "Metadata file '...\Release\project.dll' could not be found in Visual Studio"

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