(Windows only) If an earlier version of Application Server was installed using special characters or DOS-style short names in the program directory path, subsequent in-place upgrades to Application Server 9.1 will fail if those same directory path names are used.
For example, if Application Server 8.2 was installed in either:
C:\Program Files (x86)\dirs\appserver c:\progra~2\dirs\appserver
Attempts to perform an in-place upgrade to 9.1 will fail because the installer cannot convert the short names or special characters to the required long name format.
Installing Application Server using a path name that contains special characters or the DOS-style short name truncation (such as progra~2) is strongly discouraged because it impedes subsequent upgrade installations. If such an installation exists, either reinstall it using long path names before upgrading, or install the new version of Application Server in an entirely new directory.