ASP.NET : Could not load file or assembly Error (at build time)

and if I remove MySQL.data.dll from the project BIN folder then another error as described below is occur  (only when I run specific page):

check bin folder
do you have MySql.Data.dll here?
if not, you can check "Copy Local" to true

By the way Project is running successful.

In a one .aspx page I have used the following Code :

<%@ Register TagPrefix="telerik" Namespace="Telerik.Web.UI" Assembly="Telerik.Web.UI" %>

<%@ Register assembly="System.Web.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" namespace="System.Web.UI.WebControls" tagprefix="asp" %>

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included "<telerik:RadGrid>" and attached with EntityDataSource...

<asp:EntityDataSource ID="EntityDataSource1" runat="server" ConnectionString="name=Entities1" DefaultContainerName="Entities1" EnableDelete="True" EnableFlattening="true" EnableInsert="True" EnableUpdate="True" EntitySetName="heats">
                </asp:EntityDataSource>

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if not, you can check "Copy Local" to true

From where I do that?

From where I do that?
references, dll (or from bin folder)

looks like you have MySQL installed on machine, and it is in GAC, and one in the project
and they are different versions...

Installed MySQL reference does not exist in GAC. There is no name with "MySQL".

I have checked it in C:\Windows\assembly.

and add this to web config as seen on @ ID: 42271679

<compilation debug="true">

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in web.config... to see details...

I have following setting already there in web.config :

<compilation debug="true" strict="false" explicit="true" targetFramework="4.5">

and make sure web.config is pointing to the dll in bin (which is correct version 8.0 that you got from nuget)
if it is different, then delete that line and add  a reference to correct dll and set "copy local" true

set custom errors to off

<configuration>
    <system.web>
        <customErrors mode="Off"/>
    </system.web>
</configuration>

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and make sure you set your project target to correct version...

change it to x86/any cpu and try again...

<customErrors mode="Off" /> already there

Following is the Web.Config

<?xml version="1.0" encoding="utf-8"?>
<!-- 
    Note: As an alternative to hand editing this file you can use the 
    web admin tool to configure settings for your application. Use
    the Website->Asp.Net Configuration option in Visual Studio.
    A full list of settings and comments can be found in 
    machine.config.comments usually located in 
    \Windows\Microsoft.Net\Framework\v2.x\Config 
-->
<configuration>
  <configSections>
    <sectionGroup name="businessObjects">
      <sectionGroup name="crystalReports">
        <section name="rptBuildProvider" type="CrystalDecisions.Shared.RptBuildProviderHandler, CrystalDecisions.Shared, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692fbea5521e1304, Custom=null" />
      </sectionGroup>
    </sectionGroup>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  </configSections>
  <appSettings>
    <add key="CrystalImageCleaner-AutoStart" value="true" />
    <add key="CrystalImageCleaner-Sleep" value="60000" />
    <add key="CrystalImageCleaner-Age" value="120000" />
    <add key="aspnet:MaxHttpCollectionKeys" value="5000" />
  </appSettings>
  <!--
    For a description of web.config changes see http://go.microsoft.com/fwlink/?LinkId=235367.

    The following attributes can be set on the <httpRuntime> tag.
      <system.Web>
        <httpRuntime targetFramework="4.5" />
      </system.Web>
  -->
  <system.web>
    <!-- 
            Set compilation debug="true" to insert debugging 
            symbols into the compiled page. Because this 
            affects performance, set this value to true only 
            during development.

            Visual Basic options:
            Set strict="true" to disallow all data type conversions 
            where data loss can occur. 
            Set explicit="true" to force declaration of all variables.
        -->
    <httpRuntime executionTimeout="120" maxRequestLength="4096" useFullyQualifiedRedirectUrl="false" minFreeThreads="8" minLocalRequestFreeThreads="4" appRequestQueueLimit="100" />
    <compilation debug="true" strict="false" explicit="true" targetFramework="4.5">
      <assemblies>
        <add assembly="CrystalDecisions.CrystalReports.Engine, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692fbea5521e1304" />
        <add assembly="CrystalDecisions.ReportSource, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692fbea5521e1304" />
        <add assembly="CrystalDecisions.Web, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692fbea5521e1304" />
        <add assembly="CrystalDecisions.CrystalReports.Design, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304" />
        <add assembly="CrystalDecisions.Data.AdoDotNetInterop, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304" />
        <!--<add assembly="System.Xml.Linq, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>-->
        <add assembly="CrystalDecisions.Shared, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304" />
        <add assembly="MySql.Data, Version=8.0.8.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
        <add assembly="CrystalDecisions.ReportAppServer.ClientDoc, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692fbea5521e1304" />
        <add assembly="System.Security, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
        <add assembly="System.Data.Entity.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
        <add assembly="System.Data.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="System.Web.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="System.ComponentModel.DataAnnotations, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
      </assemblies>
      <buildProviders>
        <add extension=".rpt" type="CrystalDecisions.Web.Compilation.RptBuildProvider, CrystalDecisions.Web, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692fbea5521e1304" />
        <add extension=".edmx" type="System.Data.Entity.Design.AspNet.EntityDesignerBuildProvider" />
      </buildProviders>
    </compilation>
    <pages theme="Combo" controlRenderingCompatibilityVersion="3.5" clientIDMode="AutoID">
      <namespaces>
        <clear />
        <add namespace="System" />
        <add namespace="System.Collections" />
        <add namespace="System.Collections.Generic" />
        <add namespace="System.Collections.Specialized" />
        <add namespace="System.Configuration" />
        <add namespace="System.Text" />
        <add namespace="System.Text.RegularExpressions" />
        <!--<add namespace="System.Linq"/>
        <add namespace="System.Xml.Linq"/>-->
        <add namespace="System.Web" />
        <add namespace="System.Web.Caching" />
        <add namespace="System.Web.SessionState" />
        <add namespace="System.Web.Security" />
        <add namespace="System.Web.Profile" />
        <add namespace="System.Web.UI" />
        <add namespace="System.Web.UI.WebControls" />
        <add namespace="System.Web.UI.WebControls.WebParts" />
        <add namespace="System.Web.UI.HtmlControls" />
      </namespaces>
      <controls>
        <add assembly="AjaxControlToolkit" namespace="AjaxControlToolkit" tagPrefix="AjaxToolKit" />
        <add tagPrefix="telerik" namespace="Telerik.Web.UI" assembly="Telerik.Web.UI" />
        <add tagPrefix="qsf" namespace="Telerik.QuickStart" />
      <add tagPrefix="ef" assembly="Microsoft.AspNet.EntityDataSource" namespace="Microsoft.AspNet.EntityDataSource" /></controls>
    </pages>
    <authentication mode="Windows" />
    <customErrors mode="Off" />
    <httpHandlers>
      <add verb="GET" path="CrystalImageHandler.aspx" type="CrystalDecisions.Web.CrystalImageHandler, CrystalDecisions.Web, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692fbea5521e1304" />
      <add path="Telerik.Web.UI.WebResource.axd" verb="*" type="Telerik.Web.UI.WebResource" validate="false" />
    </httpHandlers>
  <membership defaultProvider="MySQLMembershipProvider">
      <providers>
        <remove name="MySQLMembershipProvider" />
        <add name="MySQLMembershipProvider" type="MySql.Web.Security.MySQLMembershipProvider, MySql.Web, Version=8.0.8.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" connectionStringName="LocalMySqlServer" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="true" applicationName="/" requiresUniqueEmail="false" passwordFormat="Clear" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="7" minRequiredNonalphanumericCharacters="1" passwordAttemptWindow="10" passwordStrengthRegularExpression="" />
      </providers>
    </membership><profile defaultProvider="MySQLProfileProvider">
      <providers>
        <remove name="MySQLProfileProvider" />
        <add name="MySQLProfileProvider" type="MySql.Web.Profile.MySQLProfileProvider, MySql.Web, Version=8.0.8.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" connectionStringName="LocalMySqlServer" applicationName="/" />
      </providers>
    </profile><roleManager defaultProvider="MySQLRoleProvider">
      <providers>
        <remove name="MySQLRoleProvider" />
        <add name="MySQLRoleProvider" type="MySql.Web.Security.MySQLRoleProvider, MySql.Web, Version=8.0.8.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" connectionStringName="LocalMySqlServer" applicationName="/" />
      </providers>
    </roleManager><siteMap defaultProvider="MySqlSiteMapProvider">
      <providers>
        <remove name="MySqlSiteMapProvider" />
        <add name="MySqlSiteMapProvider" type="MySql.Web.SiteMap.MySqlSiteMapProvider, MySql.Web, Version=8.0.8.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" connectionStringName="LocalMySqlServer" applicationName="/" />
      </providers>
    </siteMap><webParts>
      <personalization defaultProvider="MySQLPersonalizationProvider">
        <providers>
          <remove name="MySQLPersonalizationProvider" />
          <add name="MySQLPersonalizationProvider" type="MySql.Web.Personalization.MySqlPersonalizationProvider, MySql.Web, Version=8.0.8.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" connectionStringName="LocalMySqlServer" applicationName="/" />
        </providers>
      </personalization>
    </webParts></system.web>
  <!-- 
        The system.webServer section is required for running ASP.NET AJAX under Internet
        Information Services 7.0.  It is not necessary for previous version of IIS.
    -->
  <system.webServer>
    <validation validateIntegratedModeConfiguration="false" />
    <handlers>
      <add name="Telerik.Web.UI.WebResource" path="Telerik.Web.UI.WebResource.axd" verb="*" type="Telerik.Web.UI.WebResource" />
      <!--<add name="Telerik.Web.UI.WebResource"  path="Telerik.Web.UI.WebResource.axd" verb="*" type="Telerik.Web.UI.WebResource, Telerik.Web.UI, Version=[ASSEMBLY_VERSION], Culture=neutral, PublicKeyToken=121fae78165ba3d4" />-->
      <add name="CrystalImageHandler.aspx_GET" verb="GET" path="CrystalImageHandler.aspx" type="CrystalDecisions.Web.CrystalImageHandler, CrystalDecisions.Web, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692fbea5521e1304" preCondition="integratedMode" />
      <add name="Browser Link for HTML" path="*.html" verb="*" type="System.Web.StaticFileHandler, System.Web, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" resourceType="File" preCondition="integratedMode" />
    </handlers>
  </system.webServer>
  <runtime>
    <assemblyBinding appliesTo="v2.0.50727" xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="itextsharp" publicKeyToken="8354ae6d2174ddca" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-4.1.2.0" newVersion="4.1.2.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="MySql.Data" publicKeyToken="c5687fc88969c44d" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-6.5.3.0" newVersion="6.5.3.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
  <businessObjects>
    <crystalReports>
      <rptBuildProvider>
        <add embedRptInResource="true" />
      </rptBuildProvider>
    </crystalReports>
  </businessObjects>
  <system.data>
    <DbProviderFactories>
      <remove invariant="MySql.Data.MySqlClient" />
      <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=8.0.8.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
    </DbProviderFactories>
  </system.data>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    <provider invariantName="MySql.Data.MySqlClient" type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6, Version=8.0.8.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d"></provider></providers>
  </entityFramework>
<connectionStrings>
    <remove name="LocalMySqlServer" />
    <add name="LocalMySqlServer" connectionString="" providerName="MySql.Data.MySqlClient" />
  <add name="Entities" connectionString="metadata=res://*/App_Code. Model.csdl|res://*/App_Code. Model.ssdl|res://*/App_Code. Model.msl;provider=MySql.Data.MySqlClient;provider connection string=&quot;server=ABCD;user id=root;persistsecurityinfo=True;database=XYZ&quot;" providerName="System.Data.EntityClient" /></connectionStrings></configuration>

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Main error is at here :

You're using all the pre-release versions of MySQL. You might want to try using the latest release versions. If you look at your error, it's not because it can't find the assembly, it's because it can't verify the Strong Name signature.

Ok how do I resolve that...

Firstly, I would uninstall all the prerelease versions from your Package Manager, and then re-install the release versions.

In your Package Manager, there is a tickbox next to the search that says Include prerelease - untick that and you'll only see release versions. Select the ones you need to re-install.

New Error after uninstalling pre-releases and lnstalling latest one.

.

Checked the database connections. It seems Ok.

looks like you either provided no password or you did not set password for your MySQL db...

@Hainkurt & @Chris Stanyon,

I have modify Connection and applied password also.

are you trying to use root user?
create another user and set password and try to login with that user, not the root account...

Yes I have passed credentials for separate user.

And on testing the connection. It shows connection successful.

Ok,

Let me try using creating new .aspx page.

See,

Now its thrown back me to this error

ID: 42271679

make sure you have this dll in bin folder "MySql.Data.Entity.dll"

Aah,

How to get rid of this problem?

Again getting the error "Access denied for user 'abc'@'xyz.COM' (using password: NO).

New .aspx generated and then try. Also database  connections are ok.

Access denied for user 'abc'@'xyz.COM' (using password: NO)

are you sure you put connection string corrcet?
what are those ' in this message?
it should say

Access denied for user 'abc@xyz.COM' (using password: NO)

looks like you added some more ' inside your connection string...

<connectionStrings>
    <add name="Entities" connectionString="metadata=res://*/App_Code.Model.csdl|res://*/App_Code.Model.ssdl|res://*/App_Code.Model.msl;provider=MySql.Data.MySqlClient;provider connection string=&quot;server=MYSERVER;user id=MYID;persistsecurityinfo=True;database=MYDATABASE&quot;" providerName="System.Data.EntityClient" />
  </connectionStrings>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
  </entityFramework>

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what is "&quot;" inside string? Line 2

also, what exactly you put here "user id=MYID"

user id=abc@xyz.COM

???

Ohh Sorry,

It's "abc" only.

Hi Both the Experts,

Your suggestions have really worked for me.

After setting up the new database connection and Entity Data Source my issue got resolved.

Thank You again for your warm support.