anchor.diff:  validate_user_ctx(#helper{name = StorageType}, UserCtx) ->
       validate_user_ctx(StorageType, UserCtx);
   
  +
  +validate_user_ctx(StorageType = ?WEBDAV_HELPER_NAME, UserCtx) ->
  +    FieldsBase = expected_user_ctx_params(StorageType),
  +    Fields = case UserCtx of
  +        #{<<"credentialsType">> := <<"none">>} ->
  +            FieldsBase;
  +        #{<<"credentialsType">> := _} ->
  +            % make "credentials" required rather than optional
  +            [<<"credentials">> | remove_field(<<"credentials">>, FieldsBase)];
  +        _ ->
  +            FieldsBase
  +    end,
  +    validate_fields(Fields, UserCtx);
  +
   validate_user_ctx(StorageType, UserCtx) ->
       Fields = expected_user_ctx_params(StorageType),
  -    Fields2 = case {StorageType, UserCtx} of
  -        {?WEBDAV_HELPER_NAME, #{<<"credentialsType">> := Type}} when
  -            Type /= <<"none">> ->
  -            % todo VFS-5304 verify parameters
  -            % todo i. e. when type == oauth2 and insecure == true token cannot be empty
  -            [<<"credentials">> | Fields -- [{optional, <<"credentials">>}]];
  -        _ ->
  -            Fields
  -    end,
  -    validate_fields(Fields2, UserCtx).
  +    validate_fields(Fields, UserCtx).
  +
   
   
   %%--------------------------------------------------------------------
  
positive.code:             };
          (Key, Value) -> #{Key => Value}
      end, Params),
      filter_fields(expected_user_ctx_params(HelperName), Transformed);
  
  prepare_user_ctx_params(HelperName, Params) ->
      filter_fields(expected_user_ctx_params(HelperName), Params).
  
negative.code: %%--------------------------------------------------------------------
  -spec prepare_user_ctx_params(name(), ctx()) -> ctx().
  prepare_user_ctx_params(HelperName = ?WEBDAV_HELPER_NAME, Params) ->
      Ctx = maps_flatmap(fun
          (Key = <<"onedataAccessToken">>, Token) when byte_size(Token) > 0 ->
              {ok, AdminId} = user_identity:get_or_fetch_user_id(Token),
              #{
  