Olli73

Is at this place something filled in "restResponse1.Content"? Is the value later (after the Handler) filled? And what is the StatusCode of the response?

In case of ExecuteAsync, have you used the ACompletionHandler Parameter instead of the Afterexecute event and also set the ASynchronized Parameter to true?

Instead of creating your own thread/task, you could/should use "RestRequest1.ExecuteAsync(...)".

Do you use a DLL and have also in Windows event log something with "KERNELBASE.dll"? I could only solve such an issue by including the DLL code into program.

Download works out of the box, upload not. You must have a PHP Script, a CGI, a ISAPI dll or an own server to be able to upload files.

What did you install / configure on Apache server side to accept uploading files?

Not much information. I would also create a logging in the ISAPI dll.

Not sure, my experience with IIS is a long time ago, but it could be here: %SystemDrive%\inetpub\logs\LogFiles

Are you loading DLL's or other files you expect in root folder?

Servers mostly send only an "internal error", so that hackers have not much information about an issue (Vulnerability). So only a log on server can tell you more.

Your answer body in readable format: Could be an issue in your dll or other internal issues. Is your DLL 32 or 64 bit and it is propper configured in IIS? EDit: You must search / find a server log...

So you can add a sub item: LsubItem := ListView1.Items.Add; LSubItem.Text := 'Sub-Item'; LSubItem.Parent := LItem; But I think you should try TListBox. FMX list box is more comparable to VCL list view.

try OnPostedData event

Which error message? At which place (event) are you?

You try to read "parameters", but send data in body!? Then you must read body of request,