On Fri, 16 Dec 2016 04:51:16 GMT, Rey Valeza wrote: 

auto f = "filename" in req.files;
try
{
	moveFile(f.tempPath, Path("./public/uploaded/images") ~ f.filename);
}

...

but my app crashes. I tried using a form that includes an input of type 'file' but I am

See documentation about 'in' operator: https://dlang.org/spec/hash-map.html#testing_membership

You have to test f variable before any usage.

Side note: It is crucial to be able to catch memory errors when you work with D. Use next code in Linux environment and collect application's stdout and strerr to some log files to have trace for all cases of null pointer access or unhandled exceptions. 

shared static this()
{
	import etc.linux.memoryerror;
	static if (is(typeof(registerMemoryErrorHandler)))
		registerMemoryErrorHandler();
...