"The remote server returned an error: (400) Bad Request when downloading outlook.office365.com and outlook.live.com ical/ics file using WebRequest.Create()

Question

"The remote server returned an error: (400) Bad Request when downloading outlook.office365.com and outlook.live.com ical/ics file using WebRequest.Create()

John Yim 11

I'm getting "The remote server returned an error: (400) Bad Request" when trying to download outlook.office365.com and outlook.live.com ical/ics file using WebRequest.Create(). For example:

var outlook = "https://outlook.office365.com/owa/calendar/1553ff8f8cbf4066b750e3727958f281@masked/46044022e24c45469dee6721bf92c6374486754768175751168/calendar.ics";
HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(outlooklive);
myRequest.Method = "GET";
WebResponse myResponse = myRequest.GetResponse();
myResponse.Close();

However it works for google and icloud calendar.
Any idea why?

Ken Tucker 5,861 Reputation points

2022-06-10T00:45:50.797+00:00

I would use the HttpClient class instead of the HttpWebRequest. The HttpClient supports the newer web standards

John Yim 11

Thanks @Ken Tucker , I also tried that, it didn't work for outlook either. Return message "Response status code does not indicate success: 400 ()."

            try	  
            {  
                var outlook = "https://outlook.office365.com/owa/calendar/1553ff8f8cbf4066b750e3727958f281@masked/46044022e24c45469dee6721bf92c6374486754768175751168/calendar.ics";  
                HttpResponseMessage response = await client.GetAsync(outlook);  
                response.EnsureSuccessStatusCode();  
                string responseBody = await response.Content.ReadAsStringAsync();  
  
                Console.WriteLine(responseBody);  
            }  
            catch(HttpRequestException e)  
            {  
                Console.WriteLine("\nException Caught!");	  
                Console.WriteLine("Message :{0} ",e.Message);  
            }

It was working few days ago then suddenly stop working.

Ken Tucker 5,861 Reputation points

2022-06-11T14:12:28.227+00:00

Try running something like Fiddler or Wireshark to see what is going on when you make the call. Maybe it will show what is happening
John Yim 11 Reputation points

2022-06-12T00:34:37.7+00:00

We found the fix: outlook suddenly requires user-agent value in the header. Need to add something like httpRequest.UserAgent = "blah";

1 answer

Your answer

Ken Tucker 5,861 Reputation points

2022-06-10T00:45:50.797+00:00

I would use the HttpClient class instead of the HttpWebRequest. The HttpClient supports the newer web standards
John Yim 11 Reputation points

2022-06-10T00:56:54.113+00:00

Thanks @Ken Tucker , I also tried that, it didn't work for outlook either. Return message "Response status code does not indicate success: 400 ()."

try { var outlook = "https://outlook.office365.com/owa/calendar/1553ff8f8cbf4066b750e3727958f281@masked/46044022e24c45469dee6721bf92c6374486754768175751168/calendar.ics"; HttpResponseMessage response = await client.GetAsync(outlook); response.EnsureSuccessStatusCode(); string responseBody = await response.Content.ReadAsStringAsync(); Console.WriteLine(responseBody); } catch(HttpRequestException e) { Console.WriteLine("\nException Caught!"); Console.WriteLine("Message :{0} ",e.Message); }

It was working few days ago then suddenly stop working.
Ken Tucker 5,861 Reputation points

2022-06-11T14:12:28.227+00:00

Try running something like Fiddler or Wireshark to see what is going on when you make the call. Maybe it will show what is happening
John Yim 11 Reputation points

2022-06-12T00:34:37.7+00:00

We found the fix: outlook suddenly requires user-agent value in the header. Need to add something like httpRequest.UserAgent = "blah";

Answer 1

John Yim 11

Found the fix: need to have something in the header User-Agent

Share via

"The remote server returned an error: (400) Bad Request when downloading outlook.office365.com and outlook.live.com ical/ics file using WebRequest.Create()

1 answer

Your answer