UnityWebRequest.Put() not working on WebGL

Just not working..
error: Unknown Error
method: PUT
isNetworkError: True
isHttpError: False
responseCode: 0
responseHeaders: (null)

From Editor -- everything fine.
From Standalone versions -- everything fine.
In the WebGL -- all methods except PUT -- works fine (some problems with asset bundles, discussed last week).

We checked our server traffic -- from WebGL version it receives only OPTIONS query.
Server reply:
< Server: nginx/1.14.0
< Date: Thu, 31 Jan 2019 21:51:36 GMT
< Connection: keep-alive
< Access-Control-Allow-Origin: *
< Access-Control-Allow-Credentials: true
< Access-Control-Allow-Methods: GET, PUT, POST, DELETE, HEAD
< Access-Control-Allow-Headers: Accept, X-Access-Token, X-Application-Name, X-Request-Sent-Time
< Access-Control-Max-Age: 604800
< Vary: Accept-Encoding, Origin

After that -- silence...

I was forced to return to the WWW class... But what is it'll be removed in the next update ?!

P.S. We checked incoming queries from standalone version to the our server... There are no OPTIONS query AT ALL !! Only PUT.

Is it my fault, dear devs ?

 

Necroing this post since I stumbled across it with the same issue and OP never got a response. That OPTIONS request is an additional request sometimes made by browsers for enhanced security called a pre-flight request. The server should respond to this request in order to allow the original request to go through. See the link below for more information.

https://stackoverflow.com/questions/29954037/why-is-an-options-request-sent-and-can-i-disable-it