I keep getting this error about 90% through the installation. As per answer to another v. similar thread I have checked via Command Prompt tasklist/m function that there are no other processes or applications using the file. So what now ? Any suggestions most welcome.
It would appear that library file is used in Oracle. Are you wanting to use this within QGIS? If not then you could consider installing and running the OSGeo4W Network Installer.
When you run it, select the Advanced Install option and follow through the instructions until you see the Select Packages menu. Type "oracle" in the search and select an option that doesn't involve installing it (e.g.
Keep as shown in the red box).
Note: This is purely conjecture on my part as I haven't come across this issue before.
I had the same problem with QGIS 2.18.12. Before there was installed version 2.18.11 which I deinstalled correctly. So I couldn't believe that oracle is the reason. In pure distress I cleared up my C:-device. This solved the problem.