diff --git a/scrapy/http/request/form.py b/scrapy/http/request/form.py
index 2182b9b53..8b29aae4b 100644
--- a/scrapy/http/request/form.py
+++ b/scrapy/http/request/form.py
@@ -52,7 +52,7 @@ class FormRequest(Request):
 
         method = kwargs.pop('method', form.method).upper()
         if method not in cls.valid_form_methods:
-            raise ValueError('Invalid form method in chosen form')
+            method = 'GET'
 
         return cls(url=url, method=method, formdata=formdata, **kwargs)
 
diff --git a/tests/test_http_request.py b/tests/test_http_request.py
index 8fdafb286..258b48dce 100644
--- a/tests/test_http_request.py
+++ b/tests/test_http_request.py
@@ -1107,11 +1107,12 @@ class FormRequestTest(RequestTest):
 
         for method in self.request_class.valid_form_methods:
             response = _buildresponse(body % method)
-            r1 = self.request_class.from_response(response)
-            self.assertEqual(r1.method, method)
+            r = self.request_class.from_response(response)
+            self.assertEqual(r.method, method)
 
         response = _buildresponse(body % 'UNKNOWN')
-        self.assertRaises(ValueError, self.request_class.from_response, response)
+        r = self.request_class.from_response(response)
+        self.assertEqual(r.method, 'GET')
 
 
 def _buildresponse(body, **kwargs):