[BlueOnyx:26202] LE stopped renewing

[Colin Jack]

We have a 5209R which has stopped renewing a vsite LE cert.
It has been fine for months but now when I try and renew I get the ‘red page of death’! :-/

>From the log and can see this

[Fri May 12 18:56:12 BST 2023] wellknown_path='/home/.acme//.well-known/acme-challenge'
[Fri May 12 18:56:12 BST 2023] writing token:JmiClJxHkVKF20NblApbWRrHZZ4n0iUkMRWJVGBfBQA to /home/.acme//.well-known/acme-challenge/JmiClJxHkVKF20NblApbWRrHZZ4n0iUkMRWJVGBfBQA
[Fri May 12 18:56:12 BST 2023] Changing owner/group of .well-known to root:root
[Fri May 12 18:56:12 BST 2023] url='https://acme-v02.api.letsencrypt.org/acme/chall-v3/227202166417/JRyFtQ'
[Fri May 12 18:56:12 BST 2023] payload='{}'
[Fri May 12 18:56:12 BST 2023] Retrying post
[Fri May 12 18:56:12 BST 2023] POST
[Fri May 12 18:56:12 BST 2023] _post_url='https://acme-v02.api.letsencrypt.org/acme/chall-v3/227202166417/JRyFtQ'
[Fri May 12 18:56:12 BST 2023] _CURL='curl --silent --dump-header /usr/sausalito/acme/data/http.header  -L  -g '
[Fri May 12 18:56:13 BST 2023] _ret='0'
[Fri May 12 18:56:13 BST 2023] _hcode='0'
[Fri May 12 18:56:13 BST 2023] code='200'
[Fri May 12 18:56:13 BST 2023] trigger validation code: 200
[Fri May 12 18:56:13 BST 2023] Pending, The CA is processing your order, please just wait. (1/30)
[Fri May 12 18:56:13 BST 2023] sleep 2 secs to verify again
[Fri May 12 18:56:15 BST 2023] checking
[Fri May 12 18:56:15 BST 2023] url='https://acme-v02.api.letsencrypt.org/acme/chall-v3/227202166417/JRyFtQ'
[Fri May 12 18:56:15 BST 2023] payload
[Fri May 12 18:56:15 BST 2023] Retrying post
[Fri May 12 18:56:15 BST 2023] POST

This to my untutored eye suggests it can't write to /home/.acme//.well-known/acme-challenge?
Am I right and any suggestions on what to do please.

Thanks

Colin