Microsoft KB Archive/159402

= How to use Response Redirect in a server script =

Article ID: 159402

Article Last Modified on 10/26/2007

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APPLIES TO


 * Microsoft Active Server Pages 4.0
 * Microsoft Internet Information Server 4.0
 * Microsoft Internet Information Services 5.0

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This article was previously published under Q159402





IN THIS TASK
SUMMARY
 * Example error
 * Example ASP
 * Code to be added

REFERENCES



SUMMARY
The Redirect method of the Response object operates by sending a header to the client. This header causes the client to look to another URL location specified in the header. Because a header must come at the beginning of a document, it is not possible to place the Redirect method in a document with HTML code preceding it.

To work around this behavior you can use the buffering capabilities of the Response object. In doing this you can output HTML code into the buffer until you reach a point where you use the Redirect method. If at this point you need to redirect to another page, you clear the buffer and then issue the Response.Redirect.

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Example error
When trying to use the Response.Redirect method in a server-side script, the following error can occur when the page is accessed:

Response object error 'ASP 0156 : 80004005

Header Error

/, line 9

The HTTP headers are already written to the client browser. Any HTTP header modifications must be made before writing page content.

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Example ASP
The following example Active Server Pages (ASP) code demonstrates this concept: <%  ' Begin buffering the HTML ' Note this MUST happen before the initial  tag. Response.Buffer = True %>    HTML code before potential redirect.

<%  ' Change the following line as appropriate for your script If 1 = 1 Then Response.Clear Response.Redirect "filename.asp" End If  %>

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Code to be added
Use the following additional HTML code after the redirect: <%  ' The following causes the HTML to actually be sent to the client. ' Up to this point, no HTML has actually been downloaded to the client ' browser. Response.End %>    The above example always redirects to the file named Filename.asp.

Note Setting the Response.Buffer = True is not necessary in Windows 2000 because it is True by default.

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