Gulp error internal/child_process.js:298 throw errnoException(err, 'spawn'); Error: spawn EACCES
<p>I searched for the cause of this error and found that I have to change permissions or run gulp using sudo, but still got the same error.
Can anyone please help...</p>

<p>internal/child_process.js:298
    throw errnoException(err, 'spawn');
    ^</p>

<p>Error: spawn EACCES
    at exports._errnoException (util.js:870:11)
    at ChildProcess.spawn (internal/child_process.js:298:11)
    at exports.spawn (child_process.js:362:9)
    at exports.execFile (child_process.js:151:15)
    at ExecBuffer. (/var/www/conFusion/node_modules/gulp-imagemin/node_modules/imagemin/node_modules/imagemin-optipng/node_modules/exec-buffer/index.js:91:3)
    at /var/www/conFusion/node_modules/gulp-rev/node_modules/vinyl-file/node_modules/graceful-fs/graceful-fs.js:42:10
    at /var/www/conFusion/node_modules/gulp-cache/node_modules/cache-swap/node_modules/graceful-fs/graceful-fs.js:42:10
    at /var/www/conFusion/node_modules/gulp-imagemin/node_modules/imagemin/node_modules/vinyl-fs/node_modules/graceful-fs/graceful-fs.js:42:10
    at FSReqWrap.oncomplete (fs.js:82:15)</p>