Sharepoint online API returns: HTTP Error 400. A request header field is too long
Question
I have a loop that will loop through records in my DB, pulling information i need and then creating 3 folders & upload a file.
This works OK for like 40 records but then it starts erroring out with the below response back from sharepoint: <!DOCTYPE HTML PUBLIC \\"-//W3C//DTD HTML 4.01//EN\\"\\"http://www.w3.org/TR/html4/strict.dtd\\">\\r\\n<HTML><HEAD><TITLE>Bad Request</TITLE>\\r\\n<META HTTP-EQUIV=\\"Content-Type\\" Content=\\"text/html; charset=us-ascii\\"></HEAD>\\r\\n<BODY><h2>Bad Request - Header Field Too Long</h2>\\r\\n<hr><p>HTTP Error 400. A request header field is too long.</p>\\r\\n</BODY></HTML>
I am not sure whats going on, i read online its todo with cookies but i am using HTTPClient to send the request so i dont know how that would effect it? I also seen onlne about changing the kestrel?
Can anybody shed some light on this for me? Provide me with an easy but working solution? I dont use CSOM for integrating to sharepoint online, i use HTTP Requests, below is a sample of how i interact with sharepoint.
It seems as if i get blocked or banned temporarily cause if i wait a good bit, i can then make the same request that failed previously, and it will work! So strange.
Sample code (Used to create a resource at Sharepoint):
//Set Endpoint
var sharePointEndpoint = $"https://{hostname}/sites/{site}/_api/web/folders";
//Set default headers
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", sharePointToken); //Set token
client.DefaultRequestHeaders.Add("Accept", "application/json;odata=verbose");
//Pre-Body data setup
var metaData = new MetaDataModel();
metaData.type = "SP.Folder";
//Body data setup
var bodyModel = new ExpandoObject() as IDictionary<string, object>;
bodyModel.Add("__metadata", metaData);
bodyModel.Add("ServerRelativeUrl", location + "/" + directoryName + "/");
//Set content headers
HttpContent strContent = new StringContent(JsonConvert.SerializeObject(bodyModel));
strContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
strContent.Headers.ContentType.Parameters.Add(new NameValueHeaderValue("odata", "verbose"));
// Send request, grab response
var response = await client.PostAsync(sharePointEndpoint, strContent);
//Return response message
return response;
1 answers
solution1
0 ACCPTED 2019-09-20 09:31:01
It turns out I needed to use Content-Length header when sending the request, once done I was able to successfully communicate with sharepoint without encountering this error.
More information here: https://social.technet.microsoft.com/Forums/en-US/26459f1c-945d-4112-9200-69c5a33a37ff/sharepoint-online-rest-api-returns-http-error-400-a-request-header-field-is-too-long?forum=sharepointdevelopment
Thanks.
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