Open Form Error FRM-92050 Failed to Connect to the Server /forms/servlet:-1

Some client computers can not open any form,the following error out.

Others client computers work well.

For problem computers can not generate FRM trace.

----Error-----

FRM-92050: Failed to connect to the Server: /forms/servlet:- 1" , detail:

Java exception:

java.io.IOException: Server returned HTTP response code: 400 for URL http://xxxxxxx

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Expect any hint.

Regards

Gavin