diff --git a/debezium-connector-oracle/src/main/java/io/debezium/connector/oracle/logminer/LogMinerStreamingChangeEventSource.java b/debezium-connector-oracle/src/main/java/io/debezium/connector/oracle/logminer/LogMinerStreamingChangeEventSource.java
index 21b0961a6..1b7cac79d 100644
--- a/debezium-connector-oracle/src/main/java/io/debezium/connector/oracle/logminer/LogMinerStreamingChangeEventSource.java
+++ b/debezium-connector-oracle/src/main/java/io/debezium/connector/oracle/logminer/LogMinerStreamingChangeEventSource.java
@@ -208,10 +208,13 @@ public void commitOffset(Map<String, ?> offset) {
     }
 
     private boolean connectionProblem (Throwable e){
+        if (e.getMessage() == null || e.getCause() == null) {
+            return false;
+        }
         return e.getMessage().startsWith("ORA-03135") ||
                 e.getMessage().startsWith("ORA-12543") ||
                 e.getCause() instanceof IOException ||
-                (e.getCause() != null && e.getCause().getCause() instanceof NetException);
+                e.getCause().getCause() instanceof NetException;
 
     }
 }
diff --git a/debezium-connector-oracle/src/main/java/io/debezium/connector/oracle/logminer/TransactionalBuffer.java b/debezium-connector-oracle/src/main/java/io/debezium/connector/oracle/logminer/TransactionalBuffer.java
index d63c51ddc..fd960b402 100644
--- a/debezium-connector-oracle/src/main/java/io/debezium/connector/oracle/logminer/TransactionalBuffer.java
+++ b/debezium-connector-oracle/src/main/java/io/debezium/connector/oracle/logminer/TransactionalBuffer.java
@@ -178,7 +178,7 @@ private BigDecimal calculateSmallestScn() {
                 .map(transaction -> transaction.firstScn)
                 .min(BigDecimal::compareTo)
                 .orElseThrow(() -> new DataException("Cannot calculate smallest SCN"));
-        metrics.ifPresent(m -> m.setOldestScn(scn == null ? null : scn.longValue()));
+        metrics.ifPresent(m -> m.setOldestScn(scn == null ? -1 : scn.longValue()));
         return scn;
     }
 
diff --git a/debezium-connector-oracle/src/main/java/io/debezium/connector/oracle/logminer/TransactionalBufferMetrics.java b/debezium-connector-oracle/src/main/java/io/debezium/connector/oracle/logminer/TransactionalBufferMetrics.java
index db37b14be..8dfc8c778 100644
--- a/debezium-connector-oracle/src/main/java/io/debezium/connector/oracle/logminer/TransactionalBufferMetrics.java
+++ b/debezium-connector-oracle/src/main/java/io/debezium/connector/oracle/logminer/TransactionalBufferMetrics.java
@@ -152,7 +152,7 @@ public long getMinLagFromSource() {
 
     @Override
     public long getAverageLagFromSource() {
-        return totalLagsFromTheSource.get().toMillis()/capturedDmlCounter.get() == 0 ? 1 : capturedDmlCounter.get();
+        return totalLagsFromTheSource.get().toMillis()/(capturedDmlCounter.get() == 0 ? 1 : capturedDmlCounter.get());
     }
 
     @Override