Re: Could not load file or assembly 'App_Web...'

We precompile our code using the Web Application Project project type.
MS actually slapped my hand a bit for this and said this may have
something to do with the problem <that's your q scott;)>.

I'm not sure if your deployment method would work for us.  As it stands,
I can IISReset and clear temp files, have no new files deployed from
that point, and the error creeps up again.

Thanks for your feedback.  If I receive more information I'll be sure to
share.

-----Original Message-----
From: Discussion of building .NET applications targeted for the Web
[mailto:[email protected]] On Behalf Of Simpson, Nick
Sent: Thursday, February 15, 2007 9:17 AM
To: [email protected]
Subject: Re: [DOTNET-WEB] Could not load file or assembly 'App_Web...'

Hi Ian,

Our current way of avoiding this error happening is not to allow any
.ascx,
.aspx, .cs, or other ASP.NET files to be deployed to the live server
except
during a full build and when the site has been stopped with "iisreset
-stop"
before we copy any files over. So far in following this practice this
problem has not happened to us. Not ideal but so far it's done the job.

I have found that when this did happen on our live server it is
sometimes
preceeded by a "Could not load type" error which then either (a)
immediately
goes on to become a "Could not load file or assembly error" or (b)
eventually does this when the app is recycled.

One of my theories is that if i copy an .ascx file to my site folder
structure whilst a page with that user control is being requested by a
user
the problem can occur. I think this can sometimes cause a "Could not
load
type" exception and then the compiler gets it's knickers in a twist and
something more dramatic happens afterwards. In our case the particular
page
that exhibits the "Could not load type" exception has a Master page with
nested user controls, and other user controls that are dynamically
loaded,
and references a web service, and maybe also references a .NET 1.1 DLL,
so
there are plenty of factors that could be involved in this. Urk.

One thing i was wondering is if anyone out there precompiles their code
and
whether they have any problems? If so please let me know. I am just
wondering if precompilation might solve this completely somehow.

Nick

-----Original Message-----
From: Discussion of building .NET applications targeted for the Web
[mailto:[email protected]] On Behalf Of Ian Suttle
Sent: 15 February 2007 17:01
To: [email protected]
Subject: Re: [DOTNET-WEB] Could not load file or assembly 'App_Web...'


I've also had this error.  We have a load-balanced environment, and
store
nothing in session state.  We've narrowed the problem down to a single
user
control (nested) but we're unable to detect the problem still (the
control
looks fine).  I opened a case with Microsoft.  They recommended a hot
fix
for this issue, which did not fix it.  They then recommended I switch to
debug mode, clear my temp files for .Net, and when the error occurred
again
to send them both my /bin contents and .net temp file contents so they
could
look into it further.  They did not respond to this data.  In my latest
attempt they told me to change the batch attribute of the compilation
node
in my web.config to "false" (default is "true").  This has not helped
either.

To alleviate the occurrence I have a script which does an IISReset and
clears the .Net temp files on all servers in the farm.  Now what is
funny is
the problem appears to grow.  It starts on one server, and "spreads."
I'm
sure this is a timing issue since the last IISReset of course.

We have not resolved our problem to date.  If you find a fix other than
what
I've listed here, please share your experience.

Thanks,
Ian Suttle
http://www.iansuttle.com

-----Original Message-----
From: Discussion of building .NET applications targeted for the Web
[mailto:[email protected]] On Behalf Of Mark Kucera
Sent: Thursday, February 15, 2007 5:45 AM
To: [email protected]
Subject: Re: [DOTNET-WEB] Could not load file or assembly 'App_Web...'

Nick,

FWIW, in our environment where we had the same issue you report, we were
NOT
in a load balanced environment, and also like you, I was experiencing
the
error on localhost as well as production.

-Mark



-----Original Message-----
From: Discussion of building .NET applications targeted for the Web
[mailto:[email protected]] On Behalf Of Simpson, Nick
Sent: Thursday, February 15, 2007 7:20 AM
To: [email protected]
Subject: Re: [DOTNET-WEB] Could not load file or assembly 'App_Web...'

Hi James,

Thanks for your email. We are load-balanced (sticky-IP) and although we
generally have a rule never to use sessions unless absolutely necessary
we
might be using them... although i have to say that i have had this error
on
my localhost where load balancing doesn't come into it. Will take a look
at
this however and appreciate your help.

Nick

-----Original Message-----
From: Discussion of building .NET applications targeted for the Web
[mailto:[email protected]] On Behalf Of James Geall
Sent: 15 February 2007 12:06
To: [email protected]
Subject: Re: [DOTNET-WEB] Could not load file or assembly 'App_Web...'

Hi Nick,

This may not be the problem that you are seeing, but I noticed you
mentioned
load balancing. I am assuming that you have the session state being
stored
out of process. Do you store anything in the session that is based on a
type
that is not precompiled in a dll?

This error can occur if you are doing something similar to the
following:

1: Declare enumeration in aspx.cs file - enumeration exists in dll
compiled
on the fly by asp.net
2: Stick the enumeration in the session (on machine1)
3: Store the session out of process - cauing the enumeration to be
serialised
4: Get load balanced to another machine (machine2)
5: Session gets loaded onto the other machine(machine2)
6: File not found error occures when the session is deserialised on
(machine2)

this occurs because the randomly generated compiled assembly name is
included in the serialised object which then can't be loaded.  and
because
it is load balanced it happens unpredictably and for the lifetime of the
session. The solution is to make sure everything that you put in the
session
is in a precompiled dll with a well known name.

Hope this helps
James

On 2/9/07, Simpson, Nick <[email protected]> wrote:
>
> Hi Guys,
>
> From time to time we get a fairly serious exception on our site along
> the lines of the following:
>
> "Could not load file or assembly 'App_Web_gvvevrsq, Version=0.0.0.0,
> Culture=neutral, PublicKeyToken=null' or one of its dependencies. The
> system cannot find the file specified."
>
> The consequences of this are that a great portion of our site simply
> throws this exception (System.IO.FileNotFoundException) and ceases to
> function - bad!
>
> The fix for this is to recompile the application - a real pain in the
> butt if it happens at midnight. Also - although loads of posts out
> there happily suggest different ways of achieving a fix once the
> problem happens, practically none of them are any good on how to stop
> it ever happening in the first place. Links to a few of these posts
> follow:
>
> http://forums.asp.net/thread/1230276.aspx
> http://forums.asp.net/thread/1271201.aspx
>
> Should give you some idea of the sort of confusion that exists out
> there on this. One of the solutions suggested out there was to install
> Visual Studio 2005 SP2. I have done so. No fix. The problem still
> occurs.
>
> The circumstances under which this problem occurs in my particular
> case
> are:
>
> - A non-precompiled release build with pdbs is built to our server.
> - Once the app is running we need to update an aspx or ascx file so we
> copy this to our server.
> - We then sometimes get a "could not load type exception".
> - We take our app off load balancing so no users are on it anymore.
> - We recycle the app to try and clear this but then the "Could not
load
> file or assembly.." problem happens.
>
> Any ideas? Some people out there have suggested that this only happens
> for pages that use master pages with nested user controls. Our site
> does this so could be a pointer. However my most recent thoughts have
> turned to getting a better understanding of the compilation model in
> ASP.NET 2.0 and
seeing if
> a
> pre-compiled no-pdb release build works via the publish function in
VS.NET
> 2005. Maybe this problem never happens during a pre-compiled build.
>
> I read the following article to help me understand the new compilation
> model. Any other articles out there?
> http://odetocode.com/Blogs/scott/archive/2005/11/15/2464.aspx
>
> But i'm not quite yet at understanding how to stop this ever happening
> again. Any ideas?
>
> Nick

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