NotifyMyAndroid stopped working

I have a problem with NMA.Before It was working very well, I just checked email notification and it works.
Now each time OH want to send a notification I got:

2018-03-16 14:20:36.869 [ERROR] [] - Fatal transport error: PKIX path building failed: unable to find valid certification path to requested target
2018-03-16 14:20:36.887 [WARN ] [a.nma.internal.NotifyMyAndroid] - Can't parse response from NMA: null
java.lang.NullPointerException: null

I have update NMA add-ons, but no change.
Any idea why ?