Ddev for local development - containers won't re-start

Anyone using ddev for local development out there? I use ddev all the time and it's great.

I got grav running properly using the ddev-specific instructions at https://learn.getgrav.org/15/webservers-hosting/local-development-with-ddev.

But now, a few days later, I come to restart ddev and it won't start. I have tried ddev start, ddev restart and ddev rm && ddev start. I get error -
Failed to restart grav-admin-190414: web container failed: log=phpstatus FAILED, err=container /ddev-grav-admin-190414-web unhealthy: phpstatus FAILED

Full details

~/docker-sites/ddev/grav/grav-admin-190414 [master] $ ddev rm && ddev start
Stopping ddev-grav-admin-190414-web ... done
Stopping ddev-grav-admin-190414-dba ... done
Stopping ddev-grav-admin-190414-db ... done

Removing container: ddev-grav-admin-190414-web
Removing container: ddev-grav-admin-190414-dba
Removing container: ddev-grav-admin-190414-db
Project grav-admin-190414 has been removed.
Starting grav-admin-190414...
Using custom nginx configuration in nginx-site.conf
Custom configuration takes effect when container is created,
usually on start, use 'ddev restart' or 'ddev rm && ddev start' if you're not seeing it take effect.
Running Command Command=ip address show dev docker0
Creating ddev-grav-admin-190414-db ... done
Creating ddev-grav-admin-190414-web ... done
Creating ddev-grav-admin-190414-dba ... done

ddev-router is up-to-date
Failed to start grav-admin-190414: web container failed: log=phpstatus FAILED, err=container /ddev-grav-admin-190414-web unhealthy: phpstatus FAILED

There's no more hints about what went wrong....

I had a look in the logs to watch what went on, by doing ddev logs -f. This is the last few lines

2019-04-19 05:31:07,137 INFO success: child_exit_monitor entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
2019-04-19 05:31:07,138 INFO success: php-fpm entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
2019-04-19 05:31:07,138 INFO success: nginx entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
2019-04-19 05:31:07,138 INFO success: mailhog entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)

Any suggestions? Thanks....

Might be worth it to post your question to the ddev stackoverflow: https://stackoverflow.com/questions/tagged/ddev