Create operating system groups and users depending on your security requirements, as described in this install guide. Oracle Installation users have different requirements from Oracle Home users. User names must use only ASCII characters.

Set the TEMP environment variable.

If you have set ORA_CRS_HOME as an environment variable, then unset it before starting an installation or upgrade. Do not use ORA_CRS_HOME as a user environment variable.

If you have had an existing installation on your system, and you are using the same user account to install this installation, then unset the ORACLE_HOME, ORACLE_BASE, ORACLE_SID, and TNS_ADMIN environment variables. Unset any other environment variable or system variable set for the Oracle installation user that is connected with Oracle software homes, such as ORA_NLS10.

For example, if you have set ORACLE_HOME as a system environment variable with Oracle RAC, then it could lead to installation errors.

If you have enabled the User Account Control security feature, then Oracle Universal Installer prompts you for either your consent or your credentials when installing Oracle Database software. Provide either the consent or your Windows Administrator credentials as appropriate.