Grakn no longer starts


I have been using Grakn successfully for a while, but now it no longer starts up. The problems began yesterday when I found it could take several attempts to start the server, but now it won’t start at all, even after running grakn server stop and grakn server clean and rebooting several times. The first signs occurred after the server stop process was interrupted yesterday (not sure if that is related).
Grakn version 1.2.0
MacOS 10.13.4
Brew distribution
Problem occurs on running ‘grakn server start’ in the Terminal.
Storage and queue both succeed, then it fails to start the engine (after a long wait).
Running grakn server status reports that storage, queue and engine are all running. However, it is not possible to connect to Grakn.

Result of running ls -la /tmp/*.pid:
-rw-r–r-- 1 pauldoxey wheel 5 2 Jun 11:22 /tmp/
-rw-r–r-- 1 pauldoxey wheel 6 2 Jun 11:22 /tmp/
-rw-r–r-- 1 pauldoxey wheel 5 2 Jun 11:22 /tmp/

Result of running ps -ef | grep redis-server:
501 10687 1 0 11:22am ?? 0:04.00 /usr/local/Cellar/grakn/1.2.0/libexec/services/redis/redis-server-osx
501 18378 10494 0 11:35am ttys000 0:00.00 grep redis-server

Result of running jps:
18427 Jps
10588 CassandraDaemon
10701 Grakn
1135 Program

grakn.log (25.2 KB)cassandra.log (120.6 KB)
grakn-postprocessing.log (3.3 KB)
grakn-queue.log (1.6 KB)

I tried to upload the logs but get the html code above (not sure if any upload occurred). Happy to post them directly if that would be helpful.




Maybe you should just uninstall and reinstall grakn via brew. That should probably work.


Well, no, don’t just uninstall and reinstall :slight_smile: @pauld

@ganesh could probably help look into it this week @pauld.


Thanks Haikal - I’ll see if @ganesh can help.



@ganesh Hi Ganesh - are you going to be able to assist with this issue this week? I’m working on a proposal for a client and we’d really like to introduce Grakn as a possible solution, maybe as early as during the pitch. But for that we obviously need have been able to play around with it to explore how it might be implemented for their use case. Thanks!


Can you do a ./grakn server stop? Afterwards please report the output of the following: ls -la /tmp/*.pid, ps -ef | grep Cassandra, ps -ef | grep Grakn and ps -ef | grep redis-server?

Also, how big is the data you have in Grakn,roughly?


Hi @ganesh. I’m not a programmer so not sure if I’m starting from the right place (root directory). Here’s what I typed into the Terminal after doing a grakn server stop, and what came back:

PLD-MBP-2015:~ pauldoxey$ cd /
PLD-MBP-2015:/ pauldoxey$ ls -la /tmp/.pid
ls: /tmp/
.pid: No such file or directory
PLD-MBP-2015:/ pauldoxey$ ps -ef | grep Cassandra
501 5933 5840 0 11:40am ttys000 0:00.00 grep Cassandra
PLD-MBP-2015:/ pauldoxey$ ps -ef | grep Grakn
501 6071 5840 0 11:40am ttys000 0:00.00 grep Grakn
PLD-MBP-2015:/ pauldoxey$ ps -ef | grep redis-server
501 6093 5840 0 11:41am ttys000 0:00.00 grep redis-server
PLD-MBP-2015:/ pauldoxey$

The .gql define/insert files are just over 6 MB, with around 90,000 lines of graql input code.



@ganesh Do you need any more information from me on this? I am stuck at the moment and unable to use Grakn at all, until this is resolved. This is stalling my efforts to explore how we could use it, in mid flow (I’m in the middle of exporting data from an existing system and remodelling it in Grakn).

Do you think reinstalling Grakn might help? I’d rather understand what the underlying issue is and how to resolve it.

Many thanks!


@pauld It seems that you’ve managed to stop Grakn properly, can you attempt to start it by ./grakn server start, and copy and paste the output of the command as well as logs/grakn.log here?


@ganesh After trying for a few minutes I get the following fail message:

PLD-MBP-2015:~ pauldoxey$ grakn server start

  ________  _____     _______  __    __  __    __      _______  ___
 |   __   ||   _  \  |   _   ||  |  /  /|  \  |  |    |   _   ||   |
 |  |  |__||  | |  | |  | |  ||  | /  / |   \ |  |    |  | |  ||   |
 |  | ____ |  |_| /  |  |_|  ||  |/  /  |    \|  |    |  |_|  ||   |
 |  ||_   ||   _  \  |   _   ||   _  \  |   _    |    |   _   ||   |
 |  |__|  ||  | \  \ |  | |  ||  | \  \ |  | \   | __ |  | |  ||   |
 |________||__|  \__\|__| |__||__|  \__\|__|  \__||__||__| |__||___|

                      Grakn: The Database For AI


Starting Storage…SUCCESS
Starting Queue…SUCCESS
Starting Engine…FAILED!
Unable to start Engine
Please run ‘grakn server status’ or check the logs located under ‘logs’ directory.
PLD-MBP-2015:~ pauldoxey$

I’ve attached the grakn.log.

grakn.log (185.2 KB)



Alright, can you also copy and paste /tmp/grakn-queue.log?


Here it is:

grakn-queue.log (13.7 KB)


Hi @pauld, given that you want to get back to work to Grakn ASAP,
I would suggest to try re-download it from our website and use the fresh installation.

From your logs it’s not clear what’s failing, so it might take some time for use to find the real cause,
so maybe if there is no private data in your current Grakn dist,
do you think you could send us your current Grakn dist (zipped folder) so that we can debug it on our side?

Thank you


Hi @marco. I will see if downloading and re-installing Grakn works. Do I need to uninstall it first, and if so how?

I’m afraid some of the data in the database may be confidential, so I probably can’t share it with you.



Ok @pauld, we will try to investigate further using the logs you provided!

No need to uninstall, you can delete the grakn folder and download a new one.

Let us know if it the new downloaded version works for you


@marco @ganesh Just to let you know, my Grakn db now works fine, after downloading and reinstalling.

Thanks for your help and let me know if you find out any more about why it broke last time.