Shibboleth IdP fails to download metadata then never tries again

[shibboleth655 at lewenberg.com]

We are seeing an odd problem with downloading metadata.

Here is the sequence of events.

1. The Shibboleth IdP service has trouble downloading the metadata at 
the URL "https://idp.stanford.edu/Stanford-idps.xml'".

2. It then promises to try again in about 22 minutes.

3. However, there is *never* again a log entry indicating that 
Shibboleth IdP attempted to download the metadata at that URL. It is as 
if the IdP service stops trying.

4. This is a big problem as now our metadata is getting more and more stale.


Here are the relevant logs below:

2017-07-27 11:50:00,314 - INFO 
[org.opensaml.saml.metadata.resolver.impl.AbstractReloadingMetadataResolver:465] 
- Metadata Resolver FileBackedHTTPMetadataResolver stanford-idps: New 
metadata successfully loaded for 
'https://idp.stanford.edu/Stanford-idps.xml'
2017-07-27 11:50:00,314 - INFO 
[org.opensaml.saml.metadata.resolver.impl.AbstractReloadingMetadataResolver:306] 
- Metadata Resolver FileBackedHTTPMetadataResolver stanford-idps: Next 
refresh cycle for metadata provider 
'https://idp.stanford.edu/Stanford-idps.xml' will occur on 
'2017-07-27T19:12:30.272Z' ('2017-07-27T12:12:30.272-07:00' local time)
2017-07-27 12:21:35,186 - ERROR 
[org.opensaml.saml.metadata.resolver.impl.HTTPMetadataResolver:313] - 
Metadata Resolver FileBackedHTTPMetadataResolver stanford-idps: Error 
retrieving metadata from https://idp.stanford.edu/Stanford-idps.xml
2017-07-27 12:21:35,194 - INFO 
[org.opensaml.saml.metadata.resolver.impl.AbstractReloadingMetadataResolver:306] 
- Metadata Resolver FileBackedHTTPMetadataResolver stanford-idps: Next 
refresh cycle for metadata provider 
'https://idp.stanford.edu/Stanford-idps.xml' will occur on 
'2017-07-27T19:37:24.448Z' ('2017-07-27T12:37:24.448-07:00' local time)

(After this point, there is NEVER again a mention of 
https://idp.stanford.edu/Stanford-idps.xml&#39 in any of the logs.)


We are running Shibboleth IdP version 3.3.1 with tomcat8 on a Debian server.