A strange Java OPatch error
After installing a new version of OPatch on an Oracle database home, I got the somewhat mystifying error:
The java.library.path system variable is missing or invalid. Please set java.library.path with a correct value and retry the operation.
It turns out this is the error you get when you install a 32-bit version of OPatch into a 64-bit Oracle home.
Two things I had not realized until this: Oracle actually releases a 32-bit version of OPatch in the 12.2 series (OPatch versions are a mess, by the way); and OPatch, though written in Java, does need native system libraries.