User permissions for timers

I have a service which is working.

Have a timer, which starts this service once per year.

When in "Run as user" I use user from different project - it works perfecly.

When I create new user, adjust permissions - I receive this error:
Message ::TypeError: Cannot call method "PostMultipart" of null

I try to log table variable- have data inside, at both users

I try to log url - is correct, at both users.

Line where I have error:

var params = {
partsToSend: table /* INFOTABLE */,
url: url /* STRING */
};

var newVar = Resources["ContentLoaderFunctions"].PostMultipart(params);