Stupid or not,i don't care. Error 5 mean - access denied. Btw almost all software used same error system,which is part of system. There is possible dozenz things to make it locked,but at most time there 2 of them.
1)Remove read only from all files and folders.
2)Run it as administrator.
In can also can be locked by AV software and if you use server os you have do much more configs,since turning off system protection way different in desktop and server os.
Anyway this as least give some leads. Find the reason way easier,if you know what you need to check.
If you personaly have its locked by some different reason doens't mean this is same happends to others.
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Just ignore % value. All you need to see - grails application running at ...
After this loaded to this stage its already running and working correctly. You can move to next step.