Thanks. I will check it at the weekend okay?

No problem.

I think it comes from the fact that the path does not have a leading / when it is a directory. when it is the request that should really interpreted. My concern is that it might be better to cache the uri within the handler rather than modify the uri. or if the uri is to be modified by appending index.htm then it could be done earlier before the handles are called. (if that makes sense)

Sorry for the late replay. I did some tests and i think your usage of the serveStaic function is wrong.
In my opinion it have to be server.serveStatic("/index.htm", SPIFFS, "/test/index.htm", "max-age=86400");

This works without changing the source code.

I was under the impression that servestatic allows you to serve directories? What is the purpose of this part?

        if (!_isFile) { 
            // Base URI doesn't point to a file. Append whatever follows this
            // URI in request to get the file path.
            path += requestUri.substring(_baseUriLength); 
        }

This is a good feature as if you have 10 files in a directory you do not need a request handler for each separate file. Each handler uses a not insignificant amount of memory. It is standard web server behaviour to look for an index.htm file in a directory. Plus this used to work, before the refactoring a few commits back. That is just my two cents.

I think the important thing to emphasise is that this used to work, just fine.

Looks almost good to me.

Serving whole directories was actually what I had in mind when I added serveStatic. However due to a bug it could also be used to serve individual files. So both cases should work fine.

I moved the if(requestUri.endsWith("/")) clause inside if (!_isFile), because another valid use would be:

server.serveStatic("/info/", SPIFFS, "/info.html");

I.e. we should not try adding index.htm to the URI if target path is a file already.

I will close this pull, but thanks for pointing out the fix.