# Trouble installing cylc-8.1.0? **URL:** \ **Category:** Cylc Support\ **Created:** [January 24, 2023, 8:03pm UTC](https://cylc.discourse.group/t/trouble-installing-cylc-8-1-0/584 "2023-01-24T20:03:10Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![bencash](https://avatars.discourse-cdn.com/v4/letter/b/b2d939/32.png) [@bencash](https://cylc.discourse.group/u/bencash)\ **Post date:** [January 24, 2023, 8:03pm UTC](https://cylc.discourse.group/t/trouble-installing-cylc-8-1-0/584/1 "2023-01-24T20:03:10Z")
Has anyone run into an issue where installing cylc-flow via conda-forge hangs? I’ve run into this issue on a couple of machines now, where I get the following: (cylc810) [bcash@cola1 ~]$ conda install -c conda-forge cylc-flow Collecting package metadata (current\_repodata.json): done Solving environment: failed with initial frozen solve. Retrying with flexible solve. Solving environment: failed with repodata from current\_repodata.json, will retry with next repodata source. Collecting package metadata (repodata.json): done Solving environment: / … and then it just stays in Solving environment until the conda process runs out of memory and/or is killed. Another member of our group tried installing as well, all into new clean environments, without success. ---
**Author:** ![hilary.j.oliver](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/hilary.j.oliver/32/4_2.png) [@hilary.j.oliver](https://cylc.discourse.group/u/hilary.j.oliver)\ **Post date:** [January 24, 2023, 10:50pm UTC](https://cylc.discourse.group/t/trouble-installing-cylc-8-1-0/584/2 "2023-01-24T22:50:23Z")
Hi @bencash, Yes, unfortunately the conda environment solver seems to be really (and increasingly?) slow. I just tried it myself and quit after waiting 30 mins. You should use the new fast solver `mamba`: ```plaintext $ conda create -n cylc8 $ conda activate cylc8 $ conda install -c conda-forge mamba $ time mamba install -c conda-forge cylc-flow cylc-uiserver ... real 0m50.282s user 0m17.975s sys 0m2.604s $ cylc version 8.1.0 ``` That took 50 seconds including solve, download, and install 🎉 I’ll suggest to the team that we update our installation instructions to include this advice. ---
**Author:** ![kumarv](https://avatars.discourse-cdn.com/v4/letter/k/ecae2f/32.png) [@kumarv](https://cylc.discourse.group/u/kumarv)\ **Post date:** [January 27, 2023, 2:00am UTC](https://cylc.discourse.group/t/trouble-installing-cylc-8-1-0/584/3 "2023-01-27T02:00:54Z")
Hi, I faced the same issue: from /var/log/messages Jan 27 12:05:37 cylc8dr kernel: Out of memory: Kill process 8340 (conda) score 827 or sacrifice child Jan 27 12:05:37 cylc8dr kernel: Killed process 8340 (conda), UID 0, total-vm:10735864kB, anon-rss:7044044kB, file-rss:0kB, shmem-rss:0kB Installing and using Mamba does the trick but installing Mamba required conda-forge repo.to be specified as below: [root@cylc8dr ~]# conda install mamba Collecting package metadata: done Solving environment: failed PackagesNotFoundError: The following packages are not available from current channels: - mamba Current channels: - [main/linux-64](http://repo.anaconda.com/pkgs/main/linux-64) - /pkgs/main/noarch - /pkgs/free/linux-64 - /pkgs/free/noarch - /pkgs/r/linux-64 - /pkgs/r/noarch (removed https to avoid detection as links) To search for alternate channels that may provide the conda package you’re looking for, navigate to ``` https://anaconda.org ``` and use the search bar at the top of the page. [root@cylc8dr ~]# conda install -c conda-forge mamba Collecting package metadata: done Solving environment: done Rest of the steps are same. ---
**Author:** ![hilary.j.oliver](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/hilary.j.oliver/32/4_2.png) [@hilary.j.oliver](https://cylc.discourse.group/u/hilary.j.oliver)\ **Post date:** [January 27, 2023, 2:03am UTC](https://cylc.discourse.group/t/trouble-installing-cylc-8-1-0/584/4 "2023-01-27T02:03:48Z")
Thanks very much for that @kumarv ! You’re right. I’ll go back and correct the original post, to avoid confusing feature readers. ---
**Author:** ![bencash](https://avatars.discourse-cdn.com/v4/letter/b/b2d939/32.png) [@bencash](https://cylc.discourse.group/u/bencash)\ **Post date:** [February 7, 2023, 2:20pm UTC](https://cylc.discourse.group/t/trouble-installing-cylc-8-1-0/584/5 "2023-02-07T14:20:51Z")
Hello - This approach has stopped working for us: ```auto (clean_test) login3.frontera(1017)$ mamba install -c conda-forge cylc-flow cylc-uiserver ____ ____ / \ / \ / \ / \ / \/ \/ \/ \ / / \ / \ / \ / \ \ ____ / / \_/ \_/ \_/ \ o \__, / _/ \ _____ / ` |/ mamba (1.3.0) supported by @QuantStack GitHub: https://github.com/mamba-org/mamba Twitter: https://twitter.com/QuantStack Looking for: ['cylc-flow', 'cylc-uiserver'] conda-forge/linux-64 Using cache conda-forge/noarch Using cache pkgs/r/noarch No change pkgs/r/linux-64 No change pkgs/main/noarch 818.9kB @ 2.2MB/s 0.4s pkgs/main/linux-64 5.2MB @ 4.0MB/s 1.4s Pinned packages: - python 3.11.* Could not solve for environment specs Encountered problems while solving: - package cylc-flow-8.1.0-pyhb6b8b6f_0 requires cylc-flow-base 8.1.0 pyhd8ed1ab_0, but none of the providers can be installed The environment can't be solved, aborting the operation ``` ---
**Author:** ![hilary.j.oliver](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/hilary.j.oliver/32/4_2.png) [@hilary.j.oliver](https://cylc.discourse.group/u/hilary.j.oliver)\ **Post date:** [February 7, 2023, 8:41pm UTC](https://cylc.discourse.group/t/trouble-installing-cylc-8-1-0/584/6 "2023-02-07T20:41:11Z")
> [@bencash](#): > > Pinned packages: > > - python 3.11.\* This ☝ is the problem. Off the top of my head, Cylc currently requires Python 3.7 to 3.9 (or possibly 3.10?). I hit this myself the other day. I think it was to do with installing `mamba` first, without specifying the Python version. A “pinned” package means conda (and mamba) can’t change the version when solving the environment. But you can force it, something like this: ```console $ mamba install python==3.9 # downgrade Python $ mamba install cylc-flow cylc-uiserver # should now work ``` (Sorry for the pain!) ---
**Author:** ![bencash](https://avatars.discourse-cdn.com/v4/letter/b/b2d939/32.png) [@bencash](https://cylc.discourse.group/u/bencash)\ **Post date:** [February 7, 2023, 8:56pm UTC](https://cylc.discourse.group/t/trouble-installing-cylc-8-1-0/584/7 "2023-02-07T20:56:14Z")
Yep, this is it. We just got this to work on our group call by forcing 3.9 - I was on my way here to say we had fixed it when I saw this. 🙂 ---
**Author:** ![hilary.j.oliver](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/hilary.j.oliver/32/4_2.png) [@hilary.j.oliver](https://cylc.discourse.group/u/hilary.j.oliver)\ **Post date:** [February 7, 2023, 8:58pm UTC](https://cylc.discourse.group/t/trouble-installing-cylc-8-1-0/584/8 "2023-02-07T20:58:59Z")
BTW, @oliver.sanders has informed me that the mamba library can be used directly from `conda` now, rather than as a separate application: [https://conda.github.io/conda-libmamba-solver/getting-started/](https://conda.github.io/conda-libmamba-solver/getting-started/) ---
**Author:** ![MetRonnie](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/metronnie/32/125_2.png) [@MetRonnie](https://cylc.discourse.group/u/MetRonnie)\ **Post date:** [February 13, 2023, 10:47am UTC](https://cylc.discourse.group/t/trouble-installing-cylc-8-1-0/584/9 "2023-02-13T10:47:10Z")
cylc-flow 8.1 does support up to Python 3.10, however if you are using cylc-uiserver 1.2 for the web GUI, that only supports up to Python 3.9