Cylc 8.0rc1 released

We are pleased to announce the first release candidate for Cylc 8.

This release is suitable for early adopters and acceptance testing.

Note: Due to an issue with Jinja2 it is necessary to specify a version range for “markupsafe” if installing with pip:

$ pip install 'markupsafe<2.1' cylc-flow


Please raise questions about migration issues or feedback issues in the Cylc 8 migration category:

Future Releases

Cylc 8.0rc1 will be followed by further release candidates where we will attempt to address feedback and fix any issues reported. We will continue to develop new Cylc features after the official 8.0.0 release.

The web-based GUI (cylc-ui) will see a steady trickle of features in the following release candidates and beyond into future Cylc 8 releases. The familiar Cylc 7 “dot” and “graph” views will arrive in a future Cylc 8 release along with static graph visualisation, multi-selection and other improvements.

Beta Users

Workflows run with earlier beta versions cannot be restarted with Cylc 8.0rc1 due to a database change.

The Cylc UI Server configuration file path has changed from ~/.cylc/hub/ to ~/.cylc/uiserver/ The same for the site-config where hub has been replaced by uiserver.


Following the conda install instructions this morning installed 8.0b3.
(cylc8rc1) bcash@cheyenne1:/glade/work/bcash/workflow/graph_test> cylc --version

Is this expected?

Is this expected?

No. This suggests that Conda was unable to install the latest version of Cylc, due to an incompatibility with other packages in the environment OR due to an incompatibility with the platform.

If you were installing into an existing environment, try installing into a clean one or use of the example environment files in the reference section of the docs (these examples pin the Cylc version so it will fail rather than attempting to install an earlier version).

It was a brand-new environment, but forcing it to install 8.0rc1 revealed a bunch of incompatibilities with the base environment ncar is providing. I think we can delete this and not clutter up the announcement thread. :slight_smile: