A Common Programming Interface for Communications (CPI-C) or APPC application may stop unexpectedly with the secondary return code AP_BAD_TP_ID in Host Integration Server 2000

A Common Programming Interface for Communications (CPI-C) or APPC application that runs on a Microsoft Host Integration Server 2000-based server may return the primary return code AP_PARAMETER_CHECK with the secondary return code AP_BAD_TP_ID and the application may stop unexpectedly. This behavior occurs when the application tries to switch from one Host Integration Server node to a backup Host Integration Server node after the first Host Integration Server node is stopped.

This problem occurs when the following conditions are true:

• A single CPI-C or APPC application uses multiple sessions on a single transaction program (TP). (The application uses multiple ALLOCATE verbss with one TP_STARTED verb.)
• The application restarts multiple conversations at the same time after a Host Integration Server node has been stopped.

In certain race cases, the APPC library tries to copy uninitialized data that is too long into the TP control block. This behavior causes a corruption. This corruption marks the TP control block as not in use. Therefore, all later APPC verbs that are short of the TP_ENDED verb are rejected.

Service pack information

To resolve this problem, obtain the latest service pack for Microsoft Host Integration Server 2000. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Hotfix 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.Note Because of file dependencies, the most recent fix that contains these files may also contain additional files.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

This problem was corrected in Microsoft Host Integration Server 2000 Service Pack 2.