Unrecognized attribute 'targetFramework'. Note that attribute names are case-sensitive

Question

I'm trying to up load my site and I'm getting this error message:

Unrecognized attribute 'targetFramework'. Note that attribute names are case-sensitive.

<compilation debug="true" targetFramework="4.0">

The site works fine on my local PC but won't open when I loaded it to my host and tried to view it online.

Was it built previously on pre 4.0 framework? http://elegantcode.com/2009/11/10/unrecognized-attribute-targetframework-asp-net-4-0/ — Ta01, Sep 23 '11 at 14:42
This issue may be resolved by 4.0.3. [You can check out the KB article here.](http://support.microsoft.com/kb/2599651) @ me and let me know if this fixes your issue, I may try to get a canonical question/answer for this error and close dupes. Thanks. — , Nov 28 '11 at 20:03
When I try to install KB2599651 (64-bit download) on Win 7 x64, I get the error message that it "does not apply or is blocked by another condition on your computer". I have the same error as OP, have framework 4.0 installed and have registered it with IIS, and have chosen it as the Application Pool. — Tim, Oct 28 '12 at 11:20
Did you open in an older version of visual studio than the project was developed in? Or was it developed in Webmatrix and then opened in an older visual studio? — ruffrey, Apr 30 '13 at 14:50
If you are using Plesk Admin (Godaddy users), then 1. Log into your account. 2. Go to Websites and domains. 3. Scroll to the website which is having this problem. 4. Click on "Hosting Settings". 5. Scroll down to Microsoft ASP.NET support (Version ) and select 4.8.03761 (latest version as of Jan 2021). 6. Click OK — user3267567, Jan 07 '21 at 08:07

score 633 · Answer 1 · answered Sep 23 '11 at 14:44

633

This typically happens when you have an attribute of targetFramework="4.0" in the web.config but the App Pool is set to run ASP.NET 2.0. The targetFramework attribute is entirely unrecognized by ASP.NET 2.0 - so changing it to 2.0 won't have the desired effect.

Contact Support / Your Administrator and have the AppPool switched to 4.0.

You could also remove the attribute entirely, however if your site was coded with the 4.0 Framework, then I'm sure something else will cause an error as well.

answered Sep 23 '11 at 14:44

vcsjones

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Thanks, this solved the problem, check this link for a step by step guide to have your AppPool switched to 4.0: http://stackoverflow.com/questions/4890245/how-to-add-asp-net-4-0-as-application-pool-on-iis-7-windows-7 – user1010572 Feb 22 '12 at 10:44
thanks @vcsjones..my website is now up and running just because of you.. :) – Shiva Pareek Jan 10 '13 at 17:54
just to add to @vcsjones solution registering .net 4.0 might also be missed. You can do .net 4.0 registration using [procedure in this link](http://stackoverflow.com/questions/4890245/how-to-add-asp-net-4-0-as-application-pool-on-iis-7-windows-7) and then you need to chagne the application pool to 4.0. – Ram Jan 11 '13 at 02:31
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When I googled the error message, I found this page, with this beautiful question and even a more beautiful answer, which I alreay upvoted months ago. – Memet Olsen Jul 29 '14 at 17:44

score 83 · Answer 2 · answered Dec 16 '11 at 16:46

83

Registering the framework with IIS is what worked for me:

C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319>aspnet_regiis -i

answered Dec 16 '11 at 16:46

kenik

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This works! for 64bit is under C:\Windows\Microsoft.NET\Framework64\v4.0.30319 – OKEEngine Nov 26 '12 at 11:58
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I've had the same problem, but the regiis didn't fix it - I had to drop & recreate the entire website tree and reassign the pool for each app, and now it works... – veljkoz Dec 19 '12 at 12:22
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If this is a fresh version of IIS (no other sites running on it) or you're not worried about the hosted sites breaking with a framework change you can use -i instead of -ir while registering. – Ram Jan 11 '13 at 02:34

Alexander Zaldostanov · Answer 3 · 2018-09-01T23:30:43.690

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In IIS

Click on Application Pools

Right Click on DefaultAppPool --->> Set Application Pool Default....--->>Change .Net Version to V 4.0.

edited Sep 01 '18 at 23:30

answered May 09 '15 at 06:44

Alexander Zaldostanov

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score 45 · Answer 4 · answered Jun 20 '14 at 10:08

45

open your IIS (type inetmgr in run) and change your Application pool setting,To view large this Image Right Click Image and open image in new tab enter image description here

answered Jun 20 '14 at 10:08

Ankit

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score 27 · Answer 5 · edited Mar 12 '18 at 12:14

27

In Visual Studio menu:

Website -> Start Options -> build tab -> Select Target Framework in Dropdown box (.NET FrameWork 4)

edited Mar 12 '18 at 12:14

Jonas Äppelgran

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answered Jan 21 '12 at 13:57

elaiyaraja

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@user230910 Where's that option? – DiegoS Jan 23 '17 at 15:29
I cant remember clearly but i think this is referring to IIS – user230910 Jan 24 '17 at 05:34
Worked perfect for me MAY 2019 using Visual Studio 2019 web forms app on AWS EC2 Windows Server 2019. – Doug Null May 25 '19 at 14:15

Arsman Ahmad · Answer 6 · 2018-08-13T09:48:12.373

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I was facing the same issue while publishing my 1'st web services. I resolved it by simply doing this:

Open IIS

Click on Application Pools

Right Click on DefaultAppPool => Set Application Pool Default => Change .Net Version to V 4.0. (You can also change .Net Framework Version of your application specifically)

Hope, it'll work.

edited Aug 13 '18 at 09:48

answered Jul 11 '17 at 11:38

Arsman Ahmad

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score 9 · Answer 7 · answered Nov 07 '17 at 12:35

9

for IIS 7 try according to the given picture ... mark me helpful if it works for you.

answered Nov 07 '17 at 12:35

gm arif

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LCJ · Answer 8 · 2013-08-21T09:06:23.180

I had to register ASP.Net in IIS to get it resolved in the Windows Server 2008 R2. Sreenshot of the commands attched below

cd /d C:\Windows\Microsoft.NET\Framework\v4.0.30319

iisreset /stop

aspnet_regiis -i

iisreset /start

%systemroot%\system32\inetsrv\appcmd set config /section:isapiCgiRestriction /[path='%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_isapi.dll'].allowed:True 

%systemroot%\system32\inetsrv\appcmd set config /section:isapiCgiRestriction /[path='%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_isapi.dll'].allowed:True

enter image description here

score 7 · Answer 9 · answered Mar 17 '17 at 18:42

7

I'm using IIS Express, rather than IIS.

The problem was in the applicationhost.config file located in: {solution_folder}\.vs\config\applicationhost.config.

One of the application pool entries had a managedRuntimeVersion value of "v2.0". I changed it to "v4.0", and it worked properly.

I'm fairly sure the root cause was one of the NuGet packages I had installed recently.

    <system.applicationHost>
       <applicationPools>
          <add name="BadAppPool1" managedRuntimeVersion="v2.0" managedPipelineMode="Integrated" CLRConfigFile="%IIS_USER_HOME%\config\aspnet.config" autoStart="true" />
       </applicationPools>
    </system.applicationHost>

answered Mar 17 '17 at 18:42

NightShovel

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Nice- every single post mentioned IIS. I was using IIS Express. Thx for the fix – PhillyNJ Aug 02 '18 at 15:22
I faced the same issue with IIS Express, I simply deleted the folder `.vs` under solution folder, then re-opened the solution, and the problem is gone – Abdul Rahman Kayali Nov 11 '20 at 09:27

score 5 · Answer 10 · edited Dec 30 '12 at 07:31

5

Change the application pool to target framework 4.0 instead of classic .

RC website ->manage website->advanced setting>
the first option change from classic to framework 4 integrated.

edited Dec 30 '12 at 07:31

Mhd. Yasseen

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answered Dec 30 '12 at 06:56

dev.Magdy

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score 4 · Answer 11 · answered Aug 19 '14 at 09:33

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Open Project -> press Shift + F4 (Open properties page) -> Chose Build -> in Target Framework chose .NET Framework 4 -> OK

answered Aug 19 '14 at 09:33

Chưa biết

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score 4 · Answer 12 · answered Jul 26 '18 at 13:10

4

I also got the same issue while running my application locally which is pointing to .Net Framework 4.7.1. The bug was "Unrecognized attribute TargetFrameWork" as shown below.

But none of the above answers helped me. At last when I changed my present port (1413) number to some other value(60179) as shown below it worked fine for me.But I am not sure for the actual reason behind this , but it worked.

answered Jul 26 '18 at 13:10

Rinoy Ashokan

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I am just verifying that I have had this exact error, and I tried simply changing the port as indicated in this answer. I'm running the WCF Test Client to start this service on localhost. After changing the port number, the service was able to start. Thank you for your suggestion. – Evan Jan 29 '19 at 17:47
After trying all the suggestions only this one solved my issue. Thank you so much. – Prabo Mar 11 '20 at 15:30
IIS Express creates a new configuration for each site that you run, and it's bound to the url (host/port). This means that if you have a project using framework 2.x (2.0 to 3.5) running on some port and then later you open another project using framework 4.x in the same port you'll see that issue. The footer shows that it's running under framework 2.x and that framework 2.x doesn't recognize the "targetFramework" attribute, which started in 4.x. – drizin Dec 01 '20 at 16:44

score 3 · Answer 13 · answered Mar 07 '12 at 10:44

3

Create a new pool by selecting .Net Framework v4.0.3xxxxx

use the Manage Pipeline Mode: Integrated

Assign it to your site and done.

answered Mar 07 '12 at 10:44

Ali Adravi

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score 2 · Answer 14 · answered Dec 25 '12 at 09:10

2

To fix this problem simply click the ASP.NET Version icon in the Site Tools section of Control Panel to switch the framework to 4.0.

answered Dec 25 '12 at 09:10

Sumanuski

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score 2 · Answer 15 · edited Aug 14 '13 at 12:21

I had this error from a failed MSBuild compile, in a project file converted from an earlier version of VS into VS2010 and .NET 4.0. It was actually a Web Deployment project, and the solution that worked for me was adding the following entries into the PropertyGroup section at the start of the MSBuild file:

<ProductVersion>10.0.11107</ProductVersion>

<TargetFrameworkVersion>v4.0</TargetFrameworkVersion>

Maybe these get automatically updated when other types of project are converted in VS2010, but they were missing from my Web Deployment project file after it was converted.

score 2 · Answer 16 · answered Nov 12 '13 at 05:12

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What I did: I did change the value of Application Pool to DefaultAppPool from a previous value. You do this in the Advanced Settings (Website --> Manage Website --> Advanced Setting>.

answered Nov 12 '13 at 05:12

Eldon

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score 1 · Answer 17 · answered Jul 09 '12 at 06:51

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Just had this in VS 2010.

Fixed by editing the .sln file and changing the TargetFrameworkMoniker to have the value ".NETFramework,Version%3Dv4.0" assigned to it.

answered Jul 09 '12 at 06:51

Matt

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score 1 · Answer 18 · answered Dec 01 '20 at 16:51

If you're using IIS Express, it creates a new configuration for each site that you run, and it's bound to the url (host/port). However, when it opens a new project using the same port it doesn't refresh the configuration.

This means that if you have a project using CLR 2.0 (.NET Framework 2.0 to 3.5) running on some port and then later you open another project in the same port using CLR 4 (.NET Framework 4.x+) the new project will try to run using CLR 2, which fails - and in case it doesn't even recognize the "targetFramework" attribute.

One solution is cleaning IIS Express sites, but the easiest method is changing the port so that IIS Express will create a new site (using CLR 4) for your project.

score 0 · Answer 19 · edited Oct 21 '12 at 00:22

If you compile the files and the value of the "targetFramework" is set as being a particular version i.e. 4.0,

Make sure the host is running .net framework as the same version stated.

If not, download the .net framework.

After downloading, if it is not automatic being set in the IIS manager to be using the extension of the newly downloaded version of .net framework,

add the extension manually by going to the folder of the recently downloaded .net framework THROUGH IIS manager:

1.right-click website folder

2.go to "Properties"

3.under "virtual directory" , click "configuration"

4.edit the executable path of extension ".aspx" (of which the path being pointed to version other than the version of the recently downloaded .net framework) to the correct path which is the folder of the NEWLY downloaded version of .net framework and then select the "aspnet_isapi.dll" file.

5.click ok!

score 0 · Answer 20 · answered Feb 26 '14 at 12:43

0

Just Remove the "Target Framework 4.0" and close the bracket.

It will Work

answered Feb 26 '14 at 12:43

Vignesh

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score 0 · Answer 21 · answered Mar 20 '14 at 09:12

0

Follow these two steps:

Register the .net framework version version 4.0 (if it is not registered)

C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319>aspnet_regiis -i
In the app pool change the .net framework to v4.0

answered Mar 20 '14 at 09:12

SharpCoder

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score 0 · Answer 22 · answered Mar 26 '14 at 01:29

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If you install the IIS after the installation of .Net FrameWork. You need install the .net framework again for IIS. So all we need to do is run aspnet_regiis -i. Hope it is helpful.

answered Mar 26 '14 at 01:29

Joe.wang

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score 0 · Answer 23 · answered Sep 22 '15 at 12:54

Saw the error "Unrecognized attribute 'targetFramework'" in the 'Console output' page of Jenkins on a build server. This was after I changed the 'target framework' for several projects from '.NET Framework 3.5' to '.NET Framework 4' and committed my changes.

In Jenkins the project settings had to be changed. For the solution the 'MSBuild Version' had to be changed from 'v3.5' to 'v4.0'.

score 0 · Answer 24 · answered Oct 13 '15 at 08:47

0

Just had this issue deploying a new app to an old IIS box. The investigation led to the v4.5.1 run-time being installed but the app requiring v4.5.2

Nothing apart from installing the correct version of ASP .Net run-time was required.

answered Oct 13 '15 at 08:47

rob

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score 0 · Answer 25 · answered Dec 21 '16 at 19:38

It could be that you have your own MSBUILD proj file and are using the <AspNetCompiler> task. In which case you should add the ToolPath for .NET4.

<AspNetCompiler
    VirtualPath="/MyFacade"
    PhysicalPath="$(MSBuildProjectDirectory)\MyFacade\"
    TargetPath="$(MSBuildProjectDirectory)\Release\MyFacade"
    Updateable="true"
    Force="true"
    Debug="false"
    Clean="true"
    ToolPath="C:\Windows\Microsoft.NET\Framework\v4.0.30319\">      
</AspNetCompiler>

score 0 · Answer 26 · answered Mar 14 '17 at 07:43

0

For layering, Just change the version of targetFramework in web.config file only, the other things no need change.

answered Mar 14 '17 at 07:43

Cheah Eng Teong

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score 0 · Answer 27 · answered Sep 11 '18 at 16:50

I had the same issue and I found this nice poweshell script to update all of your app pools at the same time: https://gallery.technet.microsoft.com/scriptcenter/How-to-set-the-IIS-9c295a20

Make sure to set you $IISAppPoolDotNetVersion = "v4.0" variable at the top.

score 0 · Answer 28 · answered Feb 19 '19 at 06:49

following 2 steps will force refresh Visual Studio and IIS Express cache and usually resolve my similar issues:

Simply switch Project framework from 4+ to .Net framework 3.5 and run it
If it ran successfully you can revert it back to your desired 4+ target framework and see that it will probably work again.

score 0 · Answer 29 · answered Dec 04 '19 at 09:23

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Changing the port number for the local development helped me Thanks @Rinay Ashokan. I have done all the trouble shooting and finally found that the project configurations are stored in the IIS express for the port number.

answered Dec 04 '19 at 09:23

karthikn2411

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score -1 · Answer 30 · answered Oct 16 '15 at 19:08

For anyone having this who doesn't have IIS running on their dev PC, here's what happened to me: I had one website on, overwrote with files from a diff website that was 4 while the previous was 3.5. Got this error. Fixed it simply by changing the directory name of the website, which on a dev PC can be anything, so no problem. The above are probably more elegant to be sure, but sometimes simple works, IF you can get away with it, i.e., you're in dev rather than QA or Prod.

Unrecognized attribute 'targetFramework'. Note that attribute names are case-sensitive

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