Since TPX is a VTAM application and needs to follow all of the 3270 protocols to display data correctly, the applications also need to follow 3270 attributes in a formatted manner.
The permanent resolution is to alter the program to send the answer as a formatted screen instead of plain text.
As an interim workaround, you can temporarily discard TPXL0099 messages from the TPX LOG by using the LOG Writer Exit. The Log Writer exit is called after a TPX LOG message has been formatted but before it has been written to the LOG DD. The exit can selectively write the message to the console or tell TPX to discard the message.
IMPORTANT >>> Since TPXL0099 can have many more messages than just DATA STREAM ERROR, we strongly encourage you to only discard these on a very temporary basis until the permanent application change can be implemented.
If you leave the exit in place permanently and encounter any future problems with TPX, then you could be missing crucial diagnostic information.