Error message when ISA Server 2004 Web Proxy client users try to access an external FTP site by using passive FTP functionality: "Error Code: 502 Proxy Error" (900256)
The information in this article applies to:
- Microsoft Internet Security and Acceleration Server 2004, Enterprise Edition
- Microsoft Internet Security and Acceleration Server 2004, Standard Edition
Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base: 256986 Description of the Microsoft Windows registry SYMPTOMSConsider the following scenario: - You configure Microsoft Internet Security and Acceleration (ISA) Server 2004 to enable outgoing passive FTP traffic.
- You configure several internal client computers as ISA Server 2004 Web Proxy clients.
In this scenario, the internal Web Proxy clients can at first access external FTP sites and external Web sites. However, after several days or more, users receive the following error message when they use a Web Proxy client to access an external FTP site or an external Web site: Error Code: 502 Proxy Error. No buffer space is supported.
The WinSock implementation was unable to allocate additional memory to accommodate
the function request. (10055) Note You experience this problem only if the values for the HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/W3Proxy/Parameters registry subkey are set as follows on the computer that is running ISA Server 2004: Value name: NonPassiveFTPTransfer
Value data: 0x0 CAUSEWhen ISA Server 2004 is configured in the manner that is described in the "Symptoms" section, ISA Server 2004 leaks socket endpoint handles. Specifically, ISA Server 2004 leaks a handle every time that a file is downloaded from an external FTP server.RESOLUTIONService pack informationTo resolve this problem, obtain the latest service pack for Internet Security and Acceleration Server 2004. For more information, click the following article number to view the article in the Microsoft Knowledge Base: 891024 How to obtain the latest ISA Server 2004 service pack Hotfix InformationISA Server 2004, Standard EditionService pack informationTo resolve this problem, obtain ISA Server 2004, Standard Edition Service Pack 2 (SP2).
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
891024
How to obtain the latest ISA Server 2004 service pack
ISA Server 2004, Enterprise EditionService pack informationTo resolve this problem, obtain ISA Server 2004, Enterprise Edition Service Pack 2 (SP2).
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
891024
How to obtain the latest ISA Server 2004 service pack
Hotfix informationA supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next ISA Server 2004 service pack that contains this hotfix. To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site: Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.PrerequisitesYou must be running ISA Server 2004 Enterprise Edition to install this hotfix. You cannot install this hotfix on a computer that is running ISA Server 2004 Standard Edition.Restart requirementYou do not have to restart your computer after you apply this hotfix. However, ISA Server 2004-related services are automatically stopped and then restarted when you apply this hotfix.
Hotfix replacement informationThis hotfix does not replace any other hotfixes.File information
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel. |
| w3pinet.dll | 4.0.3440.275 | 25,368 | 03-Aug-2005 | 21:36 | x86 |
WORKAROUNDWarning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk. To work around this problem, disable passive FTP functionality in ISA Server 2004. To do this, set the following values on the HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/W3Proxy/Parameters subkey: Value name: NonPassiveFTPTransfer
Value type: REG_DWORD
Value data: 0x1 After you configure this registry entry, you must restart the ISA Server 2004 Firewall service for this change to take effect. STATUSMicrosoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in ISA Server 2004 Service Pack 2. This problem was first corrected in Internet Security and Acceleration Server 2004 Service Pack 2.
| Modification Type: | Minor | Last Reviewed: | 10/12/2006 |
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| Keywords: | kbBug kbfix kbQFE kbHotfixServer kbpubtypekc KB900256 kbAudITPRO |
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