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ASP.Net error: “The type ‘foo’ exists in both ”temp1.dll“ and ”temp2.dll" (pt 2)

Answer 1

+3 A:

Clean Temporary ASP.NET Files. It could be that control before moving has an assembly and after - an another one

abatishchev 2010-04-07 22:08:36

Thank you for the idea. I deleted everything in that directory and the problem persists. :(

Greg 2010-04-08 13:12:00

Did you do a Clean from the Build menu?

SLC 2010-04-12 12:34:03

@SLC: Try menu is good idea. But first of all I mean deleting `%Temp%\Temporary ASP.NET Files` or something like `%WINDIR%\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files`

abatishchev 2010-04-12 16:57:19

Answer 2

+1 A:

I sometimes get this with my web usercontrols. They will complain they exist twice when I edit a different file. I don't know what craziness is causing it but I know that if I press space > save on the complaining control it forces the server to recompile and it works fine after that.

rtpHarry 2010-04-07 22:11:45

Thank you for good idea!I deleted everything in the User Control. All of the markup and code behind. The only thing left was the usings, namespace, classname, and Control directive. It still failed. :(

Greg 2010-04-08 13:15:27

I wasn't suggesting to wipe out the contents of the user control, just to make any change to the control (such as press space, then delete it again) and then save it. This marks the control as "dirty" in the eyes of the compiler and forces it to recompile the control the next time you visit the page.

rtpHarry 2010-04-08 17:20:28

Sorry for being confusing. I tried just modifying it and that didn't work, so then I wiped everything and it also didn't work.

Greg 2010-04-08 21:29:16

Answer 3

+1 A:

Close all visual studio instances running.
Stop IIS (if running, otherwise stop that "devserver" thing)
Clear ASP.NET Temp file folder (completely)
Clear BIN folder
Start IIS (if running)
Start VS
Rebuild solution

riffnl 2010-04-12 12:29:18

Thanks for the suggestion. I followed these steps and the problem remains.

Greg 2010-04-12 16:01:28

Have you used the Clean Solution option? (somewhere between the IIS reset) ?

riffnl 2010-04-12 16:52:57

Clean Solution still doesn't fix it.

Greg 2010-04-12 17:03:35

Answer 4

+1 A:

Is there more than one project in your solution?

Try cleaning the /bin folder (manually). It's possible that the old build file still persists somewhere, preventing you from building...

Also, take a look at your references - maybe you're duplicating the definition of something you referenced?

This is a wild shot - but maybe you've have that .dll installed in GAC?

veljkoz 2010-04-12 12:30:17

Yes, there is more than only project in my solution. I grepped the whole solution and I can't find a duplicate reference. Both the user control and the page that uses it are in the same directory. It's not in the GAC.

Greg 2010-04-12 17:36:30

Answer 5

+1 A:

I think some of these answers may have been off the mark. I have seen this when your code-behind references a different version of the assembly than your web.config does. e.g.:

(version 1.1.0.0 referenced in aspx and 1.2.0.0 referenced in web.config)

MyFile.aspx

<%@ Register TagPrefix="cc1" Namespace="StrongNamed.Namespace" Assembly="StrongNamed, Version=1.1.0.0, Culture=neutral, PublicKeyToken=692fbea5521e1304" %>

web.config:

<assemblies>
    <add assembly="StrongNamed, Version=1.2.0.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/>
...

I have seen cases where if both versions of the assembly are in the GAC, ASP.NET will give you the error that you describe.

mjmarsh 2010-04-12 19:07:04

Thanks for the new direction. I checked and I'm not using the Assembly attribute on the Register directive anywhere in my code. I'm also not registering the control in question via the web.config.

Greg 2010-04-12 21:02:00

Answer 6

+1 A:

With a lot of projects and folders, it's possible to sometimes get the namespaces messed up, especially if you're trying to force things by using namespace declarations.

To see if this really is a problem, I'd go through all my code files - .cs and .designer.cs - and remove ALL the namespace declarations, then rebuild all to see if that fixes the problem.

You don't mention what version of Visual Studio and .net you're using, that might help too - I remember dealing with a similar problem in VS2005.

chris 2010-04-12 19:07:47

Visual Studio 2008 SP1 targeting .NET 3.5 with the WebDev server.

Greg 2010-04-12 19:24:14

This is technically a correct answer. The problem was hidden in in the markup for unrelated asmx and ashx files I had also moved. Since double-clicking these types of files opens the code-behind be default, I never thought to check them.

Greg 2010-04-13 14:12:17

The generated, designer.cs files can sometimes get out of sync, and I never did find a good way to force them to regenerate correctly.

chris 2010-04-13 16:29:30

Answer 7

+2 A:

This kind of error is due to the name space. Check the name space for all the files to make sure there is no duplicated one or name space usage error error.

sza 2010-04-12 19:10:55

This did occur directly after changing the namespace. I thought about this too, but if all I do is change the filename and classname and leave the namespace intact, the error goes away. I'll doublecheck though.

Greg 2010-04-12 19:26:25

The simplest way you can do is just remove the newly added namespace and do a search for the namespace in your project and make sure there is no duplicated one. And also check the declarative on your aspx or ascx file make sure they refer to the correct namespace.

sza 2010-04-12 19:39:24

It definitely worked when I obliterated the new namespace. I've discovered some additional information, so I'm editing the question.

Greg 2010-04-12 20:47:04

@Greg: if you put any path to the namespace in the code behind, you probably need to use exactly the same namespace (MyNamespace.newdirectory) in the register directives

sza 2010-04-12 21:40:31

This is technically a correct answer. The problem was hidden in in the markup for unrelated asmx and ashx files I had also moved. Since double-clicking these types of files opens the code-behind be default, I never thought to check them.

Greg 2010-04-13 14:12:39

Answer 8

+2 A:

UPDATE: ok, as you found, the circular reference was the wrong guess, as there are other situation that may cause similar behavior.

The more general way to describe the problem is that batching at runtime works in a very permissive way which can mask problems. Basically, we try to batch everything in one folder, but if we get a compile error when compiling that batch, we fall back to individual file compilation. In many cases that works fine, but sometimes, this can lead to a given page getting compiled twice (similar to what I described below, but for a different reason).

On the other hand, aspnet_compiler works in a strict way, where if batching fails it fails altogether and does not fall back. That's why running this tool is a great way to locate various type of issues (or latent issues) that can be far from obvious at runtime. I guess we didn't do a good job evangelizing this tool for this purpose :)

As for why renaming the file fixed it, this may be caused by it changing the ordering in which files are processed, which is a bit arbitrary. It may be that if you rename it to something else, you'll see it happen again.

Frankly, looking back I kind of wish we had made this batching behavior strict at runtime, to catch those situations earlier. The reason we chose the current fall back design was to avoid failing whenever possible, but this came with a price: when something is wrong, it's a pain to catch it :)

ORIGINAL ANSWER: In short, the problem is that when batching is turned on (and it is by default), you should avoid having directory level circular dependencies. Let me explain what I mean by that.

Here is an example. Say you have:

In folder1: page.aspx and uc2.ascx
In forder2: uc1.ascx

And say that page.aspx references uc1.ascx (via a @register directive), and that uc1.ascx references uc2.ascx. At the file level, that’s perfectly fine, but at the directory level, there is a circular dependency: folder1 references something in folder2, which references something in folder1.

Why this is problematic has to do with how batching works: when you request the page, it first tries to compile everything in folder1 together. But since folder1/page.aspx references folder2/uc1.ascx, it needs to compile folder2 before it can do folder1. But then uc1 uses uc2, meaning it must first do folder1! At this point, ASP.NET detects the situation and tries to make the best of it by compiling uc2.asc by itself. While this allows some scenarios to work, it can also cause weird things because some items end up compiled in two assemblies. Here, uc2.ascx would be both compiled by itself and with the folder1 batch.

There is actually a way to easily detect if your site has such folder level circular dependencies. From a VS console window, go to the root of your site and run:

aspnet_compiler -v foo -p .

If you have folder level circular dependencies, you’ll get some errors that look like:

/foo/Sub/UC1.ascx(2): error ASPPARSE: Circular file references are not allowed.

The cheap way to avoid this issue is what you already know: disable batching. Now at least you know why that works :)

But the better thing to do if you can is to avoid the folder level circular dependencies. If you start thinking of each folders as a ‘component’ which produces an assembly, that actually makes sense, and can help make the pieces of your site more modular.

Yes, it’s also fair to call this a ‘bug’ in the compilation system, or at least a limitation. But once you’re aware of it, it’s fairly easy to avoid.

David Ebbo 2010-04-13 05:34:15

This is a great, informative answer. While I DID NOT have a circular file reference, I got a "error ASPPARSE: Could not create type" error on two *complete unrelated* files: An asmx and an ashx. Since double-clicking these files opens the code-behind by default, I never thought to view the markup on these files when I did the move. Once I viewed the markup, it was obvious that the "Class" attribute was pointed to the wrong namespace. Fixing these two files caused my User Control to compile properly.

Greg 2010-04-13 14:10:16

David, I'm still confused as to why simply renaming the user control would cause this error to go away, even with the namespace problems in the other files. I deleted the Temporary ASP.NET Files and bin/obj directories. Could the old compiled state of the site have been stored somewhere else?

Greg 2010-04-13 14:23:29

I added an update. But to answer your question, the compiled state is not stored anywhere else. More likely, it's an effect of the arbitrary ordering in file processing I described above.

David Ebbo 2010-04-13 14:41:05

Super answer! Thank you very very much. This as been the bane of my existence for the past few days.

Greg 2010-04-13 14:55:21

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ASP.Net error: “The type ‘foo’ exists in both ”temp1.dll“ and ”temp2.dll" (pt 2)

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Server Error in '/' Application.

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