Hi,
I installed 4.2.3 on Ubuntu20 server and replaced `oxTrustConfApplication` with yours (I had to replace keystore passwords and `idpBindPassword` with mine).
I upgraded to 4.3.0. It successfully loaded configuration from ldap:
```
2021-10-13 18:18:41,988 INFO [main] [org.gluu.service.config.ConfigurationFactory] (ConfigurationFactory.java:289) - Loading configuration from 'ldap' DB...
2021-10-13 18:18:43,269 INFO [main] [org.gluu.oxtrust.service.AppInitializer] (AppInitializer.java:305) - Created persistenceEntryManager: org.gluu.persist.ldap.impl.LdapEntryManager@546d4a2 with operation service: org.gluu.persist.ldap.operation.impl.LdapOperationServiceImpl@672e6f34
2021-10-13 18:18:43,475 INFO [main] [org.gluu.service.logger.LoggerService] (LoggerService.java:159) - External log configuration: null
2021-10-13 18:18:43,475 INFO [main] [org.gluu.service.logger.LoggerService] (LoggerService.java:178) - Reloading log4j2 configuration
2021-10-13 18:18:43,542 INFO [main] [org.gluu.service.logger.LoggerService] (LoggerService.java:142) - Setting layout and loggers level to 'TEXT`, `INFO' after configuration update
2021-10-13 18:18:43,594 INFO [main] [org.gluu.service.config.ConfigurationFactory] (ConfigurationFactory.java:150) - Configuration loaded successfully.
```
Thus no json decode issues. I could not replicate your issue.
Regards.