How to intercept error when httpRuntime maxRequestLength is exceded.


M

moondaddy

I have an application where users need to upload images and in my web.config
file I have a setting like this:

<httpRuntime maxRequestLength="512" />

Which restricts image larger than 500k from being uploaded. I'm also using
the HtmlInputFile control to do the uploading. My problem is that when the
user's file size exceeds 512k, the page immediately redirects to the "The
page cannot be displayed" error page which is very confusing. The use will
think that their image is corrupt, or the website has a nasty bug in it.
The way this should be handled is instead of showing the nasty "The page
cannot be displayed" page, show a friendly page telling the user that they
exceeded the file limit and to upload a smaller image.

Is there a way to intercept this and do a redirect? and if not, is there
any other way to handle this elegantly?
 
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P

Paul Glavich [MVP - ASP.NET]

You should be able to handle this in the Application_Error event in the
Global.asax. The code below just shows some example code

void Application_Error(object sender, EventArgs e)
{
SomeStringVar = .Server.GetLastError.Message();
Server.Transfer("Errors.aspx")
Server.ClearError()
}

You could also have a web.config setting that captures that particular Http
error number and redirects accordingly. Something like :-
<configuration>
<system.web>
<customErrors defaultRedirect="GenericError.htm"
mode="RemoteOnly">
<error statusCode="500"
redirect="InternalError.htm"/>
</customErrors>
</system.web>
</configuration>

You could change (or add another entry) to the '500' for whatever error code
you want.
 
M

moondaddy

Thanks Paul. I have a few questions/comments. 1) I pasted the error page
text below so you can see the error coming back. There is no error number
so I can't use your example using the web.config file. and 2) I put a break
in the global.asax code behind to step through the code and study the error
message, but the Application_Error event doesnt fire so this must not be an
application error

Sub Application_Error(ByVal sender As Object, ByVal e As EventArgs)
Dim str As String = Server.GetLastError.Message
Log(str , EventLogEntryType.Error)
End Sub

All I know is that the webconfig file's line
<httpRuntime maxRequestLength="512" />
tells asp.net what the constraint is.

Any other ideas on how to trap this error and handle it?



The page cannot be displayed
The page you are looking for is currently unavailable. The Web site
might be experiencing technical difficulties, or you may need to adjust your
browser settings.

--------------------------------------------------------------------------

Please try the following:

a.. Click the Refresh button, or try again later.

b.. If you typed the page address in the Address bar, make sure that
it is spelled correctly.

c.. To check your connection settings, click the Tools menu, and
then click Internet Options. On the Connections tab, click Settings. The
settings should match those provided by your local area network (LAN)
administrator or Internet service provider (ISP).
d.. If your Network Administrator has enabled it, Microsoft Windows
can examine your network and automatically discover network connection
settings.
If you would like Windows to try and discover them,
click Detect Network Settings
e.. Some sites require 128-bit connection security. Click the Help
menu and then click About Internet Explorer to determine what strength
security you have installed.
f.. If you are trying to reach a secure site, make sure your
Security settings can support it. Click the Tools menu, and then click
Internet Options. On the Advanced tab, scroll to the Security section and
check settings for SSL 2.0, SSL 3.0, TLS 1.0, PCT 1.0.
g.. Click the Back button to try another link.



Cannot find server or DNS Error
Internet Explorer






--
(e-mail address removed)
Paul Glavich said:
You should be able to handle this in the Application_Error event in the
Global.asax. The code below just shows some example code

void Application_Error(object sender, EventArgs e)
{
SomeStringVar = .Server.GetLastError.Message();
Server.Transfer("Errors.aspx")
Server.ClearError()
}

You could also have a web.config setting that captures that particular Http
error number and redirects accordingly. Something like :-
<configuration>
<system.web>
<customErrors defaultRedirect="GenericError.htm"
mode="RemoteOnly">
<error statusCode="500"
redirect="InternalError.htm"/>
</customErrors>
</system.web>
</configuration>

You could change (or add another entry) to the '500' for whatever error code
you want.
 
M

[MSFT]

Hello,

I think Paul's suggestion should work. I put following code in
Application_Error, and it worked:

If Request.TotalBytes > MaxValue Then

Server.ClearError()

Response.Clear()

Response.Write "The file is too large"

End If
 
M

moondaddy

Hmmm, I tried your code below and I get the same result as before, I get the
"The page cannot be displayed" page and it seems as though the
Application_Error event isn't firing.

The page is actually a user control sitting on a aspx page and the aspx page
inherits from a base page. I don't know if this would cause the event to
not fire.

I put some breaks in the global.asax and I saw the code execute on the
Application_BeginRequest event, but it clearly isn't hitting the
Application_Error event. I also put a watch on the Response object in the
Application_BeginRequest event and saw the there was no value for
TotalBytes. below is what was listed in the watch window for TotalBytes"

TotalBytes <error: an exception of type: {System.Web.HttpException}
occurred> Integer

Any other ideas?
 
M

moondaddy

Hmmm, I tried your code below and I get the same result as before, I get the
"The page cannot be displayed" page and it seems as though the
Application_Error event isn't firing.

The page is actually a user control sitting on a aspx page and the aspx page
inherits from a base page. I don't know if this would cause the event to
not fire.

I put some breaks in the global.asax and I saw the code execute on the
Application_BeginRequest event, but it clearly isn't hitting the
Application_Error event. I also put a watch on the Response object in the
Application_BeginRequest event and saw the there was no value for
TotalBytes. below is what was listed in the watch window for TotalBytes"

TotalBytes <error: an exception of type: {System.Web.HttpException}
occurred> Integer

Any other ideas?
 
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M

[MSFT]

Hello,

Here is the web form code I use to test, you may test them on your server
to see if they can work:

<form id="Form1" method="post" enctype="multipart/form-data"
action="WebForm1.aspx" runat="server">

<INPUT id="oFile" type="file" runat="server"
NAME="oFile">

<br>

<asp:button id="btnUpload" type="submit"
text="Upload" runat="server"></asp:button>

<asp:panel ID="frmConfirmation" Visible="False"
Runat="server">

<asp:Label id="lblUploadResult"
Runat="server"></asp:Label>

</asp:panel>

</form>





Private Sub btnUpload_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles btnUpload.Click

Dim strFileName As String

Dim strFilePath As String

Dim strFolder As String



strFolder = "C:\Test\"



'Get the name of the file that is posted.

strFileName = oFile.PostedFile.FileName

strFileName = Path.GetFileName(strFileName)



'Create the directory if it does not exist.

If (Not Directory.Exists(strFolder)) Then

Directory.CreateDirectory(strFolder)

End If



'Save the uploaded file to the server.

strFilePath = strFolder & strFileName



If File.Exists(strFilePath) Then

lblUploadResult.Text = strFileName & " already exists on the
server!"

Else

oFile.PostedFile.SaveAs(strFilePath)

lblUploadResult.Text = strFileName & " has been successfully
uploaded."

End If



'Display the result of the upload.

frmConfirmation.Visible = True



End Sub


The problem may be related the web control you use. Therefore, we may begin
with a basic web form for test.

Luke
 
C

Charith

hey, this is my suggestion.

so simple.
i think u have to handle this with javascript.

in file upload control, u can check for the file size before send t
the server. if it is large, give an error. if it is in limit, send t
the server.

if u need to get the size from the server, u have to add a hidden fiel
and set the max value from the web config in the page_load event.

tell if it worked.

regards,
Charit


-
Charit
 
A

ataru

If my posted file is bigger than maxRequest in httpRuntime i can trap i
in Application_Error but the redirect to an error page doesn't works an
the process die... I obtain an outpage like classic
Cannot find server....

I didn't find a way to redirect user to an error page...

You suggest to use js client-side to check file size... but j
client-side cannot do it ... can you explain your idea in a block j
code??

*hey, this is my suggestion.

so simple.
i think u have to handle this with javascript.

in file upload control, u can check for the file size before send t
the server. if it is large, give an error. if it is in limit, send t
the server.

if u need to get the size from the server, u have to add a hidde
field and set the max value from the web config in the page_loa
event.

tell if it worked.

regards,
Charith


-
atar
 
C

Charith

just check on this, i didnt try.

http://www.experts-exchange.com/Web/Web_Languages/JavaScript/Q_20573809.html[/url - Charit
 
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M

moondaddy

My pages inherit from a base page so I don't have access to writing
attributes to the form element. You used 2 attributes that I've never used
before: enctype and action. Why are you using these and would they have
any effect on how errors are trapped in the global.asax? I'm still putting
break points on the Application_Error event and also the Global_Error event
but these events aren't executing. Can you offer any more advise on how to
trap this error so I can redirect to a page with a message to the user?
(btw: all of this code is running form a user control which contains all
the content for the page, and the page inherits from a base page)

The solution mentioned Charith in this thread looks like a good solution,
but I'm reluctant to use such JavaScript on the client due to possible
problems with downward browsers. Can anyone recommend some proven
JavaScript for this?
 
M

moondaddy

I forgot to mention, I also have this setting in my webconfig:
<customErrors mode="Off"/>
for testing. could this have any effect on how the Application_Error event
fires?
 
M

[MSFT]

Hello,

Form's Action property sets or retrieves the URL to which the form content
is sent for processing. EncType property sets or retrieves the Multipurpose
Internet Mail Extensions (MIME) encoding for the form.

Would you please post your client code for the form and <INPUT> component,
so I can know what is going on.

Regards,

Luke
 
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M

[MSFT]

Hello,

I copied your files to my server and made some changes so that it can run
in the environment. It worked as expected, code in application_error was
executed. The main change I made the files is that I use Windows
authentication. I suggest you may create a new project with Windows
authentication and add this file to the project, to see if it will work.

Luke
 
M

moondaddy

OK I'll try it. Thanks for staying with me on this one. I'll make another
post here when I do to let you know what happened.
 
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N

Nigil LaVey

Greetings all...

I had this issue too... did u all manage to come out with a workaround?

regards,
Nigil Chua
 

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