If you are passing query parameters such as arrays, Apache may double-encode them so that %5B and %5D becomes %255B and %255D for URLs that are submitted such as: ?a[b]=1&a[c]=2&d[]=3&d[]=4&d[2][e]=5 If you are making Ajax or API calls from a Javascript library (such as via jQuery or Angular) then it will encode the URI initially, then the web server (such as Apache) will 301 or...
Apache related information