Update:
I've checked oxauth.log and we see:
```
2020-06-16 08:45:09,378 ERROR [qtp575335780-20] [org.gluu.oxauth.model.crypto.OxAuthCryptoProvider] (OxAuthCryptoProvider.java:229) - Failed to find private key by kid: ab595eee-ea19-4eb2-90fb-2159a019a469_sig_rs256, signatureAlgorithm: RS256(check whether web keys JSON in persistence corresponds to keystore file.)
2020-06-16 08:45:09,379 ERROR [qtp575335780-20] [org.gluu.oxauth.model.common.AuthorizationGrant] (AuthorizationGrant.java:266) - Failed to find private key by kid: ab595eee-ea19-4eb2-90fb-2159a019a469_sig_rs256, signatureAlgorithm: RS256(check whether web keys JSON in persistence corresponds to keystore file.)
```
I think that error is referenced here:
https://github.com/GluuFederation/oxAuth/issues/1152 (but we installed the final 4.0 version)
and here:
https://support.gluu.org/identity-management/7787/the-link-in-the-document-doesnt-work/
As one of my clustered nodes works, I just copy oxauth-keys.jks from that to the failed one, I restarted the services and it seems it works now.
My questions are:
Have I been doing well copying that file?
Maybe I'll have another issues in the future?
May I update to version 4.1 to solve this issue?
Thanks a lot!