I am using CLIENT_TEXT_IO to export data into a excel file, but the data is not fully written and terminated and also gives this error: "File Creation was interrupted. Error 302000: non-Oracle exception".
This is almost always an OS problem. You have no access to the file, the file was deleted or moved, etc.
Without any extra information (you didn't even mention Forms, OS, browser or Java version you are using) and your code it is hard to tell.