What is "Data Error 907 / Server Error"?

Not sure. Seems to be a generic error message. Known solutions for this problem include:

• One person replaced the server name with the IP address in the GCD file and the data error was fixed. (Probably had issues with Sprint's caching technique or maybe a DNS lookup failure.)
• Make sure the full and complete URL is listed in your GCD file. Relative URLs are not allowed.
• If uploading a midlet, make sure the full and complete URL is listed in your .jad file. Relative URLs do not work.
• If uploading a midlet, make sure your .jar has a "META-INF/MANIFEST.mf" file (case sensitive).
• If there is an HTTP error code, such as a 404 error, returned from the server, the phone will display the Data Error 907.
• If the file is too big for the phone, it might say Data Error 907.