being in the PATH. These dlls (usually libeay32 and ssleay32) are generally found in your base php directory, and the modern windows installers add the base php directory to the PATH so that you don't need to worry about it. However, if when installing earlier versions you decided on moving libeay32, ssleay32 et al to C:\Windows\System32 instead of changing the PATH, then php will still end up with the old versions and the out of date versions will cause the same error as above. Don't fall into the trap like I did. Installing PHP extensions for IIS for the first time is sort of a baptism by fire -- you will get your hands dirty, and other suitable metaphors of nastiness.  Hopefully, you won't have to spend too many days googling around fora and restarting IIS 10 million times as I did until I finally realized both what was going on and what crazy things I'd done wrong. THIS (peter)guy really goes into terrific detail and troubleshooting, (with very good reasons and explanations of extension dependencies not listed on the current php page you're now reading): The main problem I'd been butting my head up against was extensions being reported as not found, even though the .DLLs were definitely in C:\PHP\ext, and my PATH env var was setup correctly. The error messaging during dynamic loading of implicitly-linked libraries should be more specific, telling you that in fact it is a particular dependency of a dependency which is missing -- usually