gen_server:call causes server to crash with a noproc - erlang

Question

I have a simple server (below). I can create the server with cell_tracer:start_link() and this works; I know this because when I repeat the same call, I get an already_started error. The problem is that after the server is created, using cell_tracker:get_cells() (or doing any gen_server:call(...)) on it causes the server to exit with an exception like this:
** exception exit: {noproc,{gen_server,call,[cell_tracker,get_cells]}}
in function gen_server:call/2 (gen_server.erl, line 180)
I can call the handle_call(get_cells...) directly, and I get the expected result.
I'm not sure what's happening here. It doesn't give me much information to work with, and I don't see a problem. How can I dig into this further?
-module(cell_tracker).
-behavior(gen_server).
-export([start_link/0, stop/0]).
-export([add_cell/1, del_cell/1, get_cells/0]).
-export([init/1,
handle_cast/2,
handle_call/3,
terminate/2,
handle_info/2,
code_change/3]).
%% operational api
start_link() ->
gen_server:start_link({global, ?MODULE}, ?MODULE, [], []).
stop() ->
gen_server:cast(?MODULE, stop).
%% traking api
add_cell(Cell) ->
gen_server:call(?MODULE, { add_cell, Cell }).
del_cell(Cell) ->
gen_server:call(?MODULE, { del_cell, Cell }).
get_cells() ->
gen_server:call(?MODULE, get_cells).
%% gen_server callbacks
init(Coords) ->
{ok, Coords}.
handle_cast(stop, Coords) ->
{stop, normal, Coords}.
handle_call({add_cell, Cell}, _From, Cells) ->
{reply, ok, [Cell|Cells]};
handle_call({del_cell, Cell}, _From, Cells) ->
{reply, ok, Cells -- Cell};
handle_call(get_cells, _From, Cells) ->
{reply, Cells, Cells}.
terminate(unnormal, _State) -> ok.
handle_info(_,_) -> ok.
code_change(_,State,_) -> {ok, State}.

Answer 1

register the server locally
start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
or if you register {global, ?MODULE} cast, call to {global, ?MODULE}
see gen_server

Answer 2

I have got the same problem working with python ( 2.7 ) and couchdb ( 2.1 ).
The point was I did save document without id. Here is an example
import couchdb
server = couchdb.Server('http://admin:PASSWORD#127.0.0.1:5984/')
db = server.create('numbers')
idd, revv = db.save({"taras":"vaskiv"})
after this I got this exception
431 # Store cachable responses
ServerError: (500, (u'noproc', u'{gen_server,call,[couch_uuids,create]}'))
But when I did save document with id, everything seems to work just fine.
idd, revv = db.save({"taras":"vaskiv", "_id": "55"})