HTTP 500 or Response buffer limit exceeded error when using Response.BinaryWrite in IIS

This article helps you resolve the error (HTTP 500 or Response buffer limit exceeded) that occurs when you use the Response.BinaryWrite method in Active Server Pages (ASP) to send a file.

Original product version:   Internet Information Services, Active Server Pages (ASP)
Original KB number:   944886

Consider the following scenario:

• You send a file to a client computer from a Web server on which Internet Information Services (IIS) is installed.
• You use the Response.BinaryWrite method to send the file to the client computer and the AspBufferingOn property is set to False.

In this scenario, you might receive one of the following error messages on the client computer:

• Error message 1

  HTTP 500 - Internal Server Error

• Error message 2

  Response object error 'ASP 0251 : 80004005'
  Response Buffer Limit Exceeded
  Execution of the ASP page caused the Response Buffer to exceed its configured limit.

Additionally, you might receive a message that resembles the following one in the IIS log file:

ASP_0251_:_80004005|Response_Buffer_Limit_Exceeded

This problem occurs because IIS enforces a default ASP response buffer value of 4 MB when ASP response buffering is disabled.

In most scenarios, the 4-MB buffer limit is sufficient for ASP responses that are sent to Web clients. If this limit is insufficient, use one of the following methods.

To resolve this issue when you use the Response.BinaryWrite method and ASP buffering is turned off, verify that the data that is returned to the client isn't larger than 4 MB.

If the response is larger than the 4-MB default value, this size frequently causes a poor user experience. The Web browser must receive the large response over the network. Then, the Web browser must parse and display a large HTML response.

You can use the AspBufferingOn IIS metabase property to enable or disable buffering at the application level.

To enable or disable buffering at the page level, you can use the Response.Buffer property.

If you must increase the buffer limit, select a buffer limit that allows for the largest known response size. If you don't know the largest response size in advance, you can increase the buffer limit to a large value during testing. After you finish testing, use the largest value that appears in the sc-bytes field in the IIS log file for the response that is generated for the page.

To increase the buffering limit in IIS, follow these steps:

1. Select Start, select Run, type cmd, and then select OK.

2. Type the cd /d %systemdrive%\inetpub\adminscripts command, and then select Enter.

3. Type the cscript.exe adsutil.vbs SET w3svc/aspbufferinglimit LimitSize command, and then select Enter.

   Note

   LimitSize represents the buffering limit size in bytes. For example, the number 67108864 sets the buffering limit size to 64 MB.

To confirm that the buffer limit is set correctly, follow these steps:

1. Select Start, select Run, type cmd, and then select OK.
2. Type the cd /d %systemdrive%\inetpub\adminscripts command, and then select Enter.
3. Type the cscript.exe adsutil.vbs GET w3svc/aspbufferinglimit command, and then select Enter.

When you use the Response.BinaryWrite method and ASP response buffering is disabled, you can only send 4 MB of data to the client unless the buffering limit property for the page is explicitly set. By default, the value for the bufferLimit property in IIS is 4,194,304 bytes.

Additionally, the BinaryWrite() API fails if the response to the client is larger than the buffer limit value even though ASP response buffering is turned off.