Quick search from ~~ god ~~ googleMake sure the game data folder is not stuck in readonly . Removing the . nam files may be . i dunno . BOSSAPIERRORFILEWRITEFAIL C u s e r s M e a p p datalocalfalloutNVplugins . txtUnset the readonly flag on that file or delete it . check appdata folder . for some reason it may be changed to be by default as hidden and read only . right click on the file go to properties and I assume you ' re talking about the configuration files . Uncheck read only . Go to Drive letterUsersYour nameAppDataLocalFalloutNV . find two files , open thier propertiesPlugins . fnvviewsettings and Plugins . txt . if these two files are markedchecked as hidden uncheck them , make them unhidden , otherwise , NMM will no longer allow you to add mods , or enabledisable . esp ' s it can ' t find them anymore . it also effects the data window for the vanilla launcher . It may actually be installingreinstalling the NMM or , the whole game that makes those files hidden to begin with . and is likely a waste of time , and patience . still looking into it . I ' m starting to suspect it happens with updates now and then , where NMM resets files it should leave alone , like previous . ini files .