Kibana: NPM Permission Error at Start

I've recently installed Kibana 5.4.1 on 3 new Windows 2012 R2 servers. On the first server, Kibana install went normally, I installed Kibana as a Windows service using NSSM, the service is functioning normally.

On the other two servers, I get the following error when trying to start Kibana as a service:

Error: EPERM: operation not permitted, open 'D:\Elastic\Kibana\kibana-5.4.1-windows-x86\optimize.babelcache.json'
at Error (native)
at Object.fs.openSync (fs.js:641:18)
at Object.fs.writeFileSync (fs.js:1347:33)
at save (D:\Elastic\Kibana\kibana-5.4.1-windows-x86\node_modules\babel-register\lib\cache.js:45:16)
at _combinedTickCallback (internal/process/next_tick.js:73:7)
at process._tickCallback (internal/process/next_tick.js:104:9)
at Module.runMain (module.js:606:11)
at run (bootstrap_node.js:393:7)
at startup (bootstrap_node.js:150:9)
at bootstrap_node.js:508:3
fs.js:641
return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);

I've seen comments online that I may need to use "NPM clean cache" but I can't figure out how to run that command or verify that the problem is cleared.

Is the NPM cache my problem? If not, where else should I be looking?

not really sure what the problem is, but you could try

npm clean
npm cache clean
and if nothing helps removing the whole folder and trying again ?

I'm not sure how to invoke "npm clean" and "npm cache clean" - npm doesn't show up in my path or as an executable program, - how do I start it?

ah sorry, that should not be the problem, you are running production version ...
looking closer at the error it seems to be a permission problem ? kibana tries to write a file and doens't have permission to do so.

Thanks, it was a combination permissions problem for the service account, and an unwritable file.

I solved this problem by changing permissions for the application and data directories, and deleting the \kibana\optimize.babelcache.json file. When I restarted the application, the JSON file was created and the application is running correctly.