org.jenkinsci.lib.envinject.EnvInjectException: java.io.IOException: remote file operation failed
The EnvInject plugin is basically attempting to load the build environment which uses configuration of JDK tools in Jenkins which fails during reinstallation of Java JDK library on the Windows slave (as per given configuration). 

This JDK configuration can be found in Global Tool Configuration (at /configureTools) for the given JDK profile which was selected in that job configuration. The installation process failed to reinstall Java JDK due to running Java process in the background (such as java -jar slave.jar) which was using these DLL files.
So it sounds like it's not possible to reinstall the same Java JDK files which are used to run the Jenkins slave process. 

The solution was to disable Install automatically option in Global Tool Configuration, as Java JDK was already installed on that slave.



Related: JENKINS-46989 - EnvInjectException: remote file operation failed.