Limited access rights for ASP.NET users is a common cause for the inability to connect to a database from a Web Forms application.
Due to limited access rights of ASP.NET user and user group accounts, data sources created as User DSNs may not be loaded. You must create the data sources for your Web Forms application as System DSNs.
The appropriate user or user group must be granted full control rights to the Oracle Client directory. For example, if the Oracle client is installed in the c:\oracle\ora9 directory, the ASPNET user (IIS 5), the IIS_WPG user group (IIS 6), or the IIS_IUSRS user group (IIS 7 and 7.5) must have full control rights to this directory.
To launch a SQL Anywhere database automatically from a Web Forms application, the appropriate user or user group must be granted at least read and execution rights to the directory indicated by the SQLANY10 or ASANY9 environment variable. The ASPNET user, the IIS_WPG user group, or the IIS_IUSRS user group must also have full control privileges to the directory that contains the database.
If your application uses an INI file to get database connection information, make sure to add the INI file to the resource file list of your .NET Web Forms project before you deploy it.
If an error message indicates that the Java VM cannot be initialized, make sure that the system CLASSPATH and JAVA_HOME environment variables have been set correctly. If an error message indicates that you are attempting to read from or write to protected memory, make sure the ASPNET user, the IIS_WPG user group, or the IIS_IUSRS user group has at least read, execute, and list folder contents permissions for the vendor's JDBC directory.
After making any changes to the directory permissions or system environment variables, restart the IIS service and either ASPNET_WP.EXE (IIS 5) or W3WP.EXE (IIS 6, IIS 7, and IIS 7.5). Alternatively, you can restart the IIS server to make sure that the changes take effect.