Recently I was facing an issue with connecting to oracle. I was keep on getting below error when trying to connect oracle through .Net Code.
Error: OCIEnvCreate failed with return code -1 but error message text was not available.
Cause of Error:
I am using Win 7 machine with Oracle Installed on it and using Oracle SQL Developer. Few days back IT team at my company push updates and for some reason this updates image has uninstalled Oracle client on my machine. Oracle Client being not installed on my system was the cause of this error.
Check for Start > All Programs > Oracle - OraClient11g_home_64bit > Application Development > and Click on SQLPlus Icon.
If that Icon brings up following error, then you need to reinstall Oracle Client in order to pass through this error.
The drive or network connection that the shortcut 'SQL Plus.lnk' refers to is unavailable. Make sure that the disk is properly inserted or the network resource is available, and then try again.
If you are able to see "SQL Command Prompt" on your machine, then you do have good copy of Oracle Client installed on your machine, so you need to verify your .Net code to see whether proper connection string is assigned and so on...
Following link might also help you...
Hope this helps you in narrow down your problem.