If you want to open java forms with Firefox, you need 32-bit ESR Firefox plus 32-bit JRE.
Deploying JRE (Native Plug-in) for Windows Clients in Oracle E-Business Suite Release 12 (Doc ID 393931.1)
R12: Recommended Browsers for Oracle E-Business Suite (Doc ID 389422.1)
Also, if you want to use 1.8 JRE, you need to code sign the EBS JAR files or they will not open with 1.8 JAVA security.
Enhanced Jar Signing for Oracle E-Business Suite (Doc ID 1591073.1)
Re: If you want to open java forms with Firefox, you need 32-bit ESR Firefox plus 32-bit JRE.
What java version is partnered to this Firefox version?
How about if I used IE ? What is the supported version?