diff --git a/src/main/java/ch/ethz/seb/sebserver/gbl/async/CircuitBreaker.java b/src/main/java/ch/ethz/seb/sebserver/gbl/async/CircuitBreaker.java
index 2493bb23..b06385e6 100644
--- a/src/main/java/ch/ethz/seb/sebserver/gbl/async/CircuitBreaker.java
+++ b/src/main/java/ch/ethz/seb/sebserver/gbl/async/CircuitBreaker.java
@@ -8,8 +8,10 @@
 
 package ch.ethz.seb.sebserver.gbl.async;
 
+import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Supplier;
 
@@ -172,7 +174,7 @@ public final class CircuitBreaker<T> {
             if (failing > this.maxFailingAttempts || currentBlockingTime > this.maxBlockingTime) {
                 // brake thought to HALF_OPEN state and return error
                 if (log.isDebugEnabled()) {
-                    log.debug("Changing state from Open to Half Open and return cached value");
+                    log.debug("Changing state from Open to Half Open");
                 }
 
                 this.state = State.HALF_OPEN;
@@ -203,7 +205,7 @@ public final class CircuitBreaker<T> {
         if (result.hasError()) {
             // on fail go to OPEN state
             if (log.isDebugEnabled()) {
-                log.debug("Changing state from Half Open to Open and return cached value");
+                log.debug("Changing state from Half Open to Open");
             }
 
             this.lastOpenTime = Utils.getMillisecondsNow();
@@ -214,7 +216,7 @@ public final class CircuitBreaker<T> {
         } else {
             // on success go to CLOSED state
             if (log.isDebugEnabled()) {
-                log.debug("Changing state from Half Open to Closed and return value");
+                log.debug("Changing state from Half Open to Closed");
             }
 
             this.state = State.CLOSED;
@@ -248,9 +250,21 @@ public final class CircuitBreaker<T> {
 
     private Result<T> attempt(final Supplier<T> supplier) {
         final Future<T> future = this.asyncRunner.runAsync(supplier);
+
         try {
             return Result.of(future.get(this.maxBlockingTime, TimeUnit.MILLISECONDS));
-        } catch (final Exception e) {
+        } catch (final InterruptedException e) {
+            if (log.isDebugEnabled()) {
+                log.debug("Attempt interruption: {}, {}", e.getMessage(), this.state);
+            }
+            return Result.ofError(e);
+        } catch (final ExecutionException e) {
+            future.cancel(false);
+            if (log.isWarnEnabled()) {
+                log.warn("Attempt error: {}, {}", e.getMessage(), this.state);
+            }
+            return Result.ofError(e);
+        } catch (final TimeoutException e) {
             future.cancel(false);
             log.warn("Max blocking timeout exceeded: {}, {}", this.maxBlockingTime, this.state);
             return Result.ofError(e);
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/lms/impl/olat/OlatLmsRestTemplate.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/lms/impl/olat/OlatLmsRestTemplate.java
index 3f67d36e..f244c1b5 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/lms/impl/olat/OlatLmsRestTemplate.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/lms/impl/olat/OlatLmsRestTemplate.java
@@ -39,28 +39,58 @@ public class OlatLmsRestTemplate extends RestTemplate {
         // Add X-OLAT-TOKEN request header to every request done using this RestTemplate
         this.getInterceptors().add(new ClientHttpRequestInterceptor() {
             @Override
-            public ClientHttpResponse intercept(final HttpRequest request, final byte[] body,
+            public synchronized ClientHttpResponse intercept(
+                    final HttpRequest request,
+                    final byte[] body,
                     final ClientHttpRequestExecution execution) throws IOException {
+
                 // if there's no token, authenticate first
                 if (OlatLmsRestTemplate.this.token == null) {
                     authenticate();
                 }
                 // when authenticating, just do a normal call
                 else if (OlatLmsRestTemplate.this.token.equals("authenticating")) {
+
+                    if (log.isDebugEnabled()) {
+                        log.debug("OLAT [authentication call]: URL {}", request.getURI());
+                    }
+
                     return execution.execute(request, body);
                 }
                 // otherwise, add the X-OLAT-TOKEN
                 request.getHeaders().set("accept", "application/json");
                 request.getHeaders().set("X-OLAT-TOKEN", OlatLmsRestTemplate.this.token);
+
+                if (log.isDebugEnabled()) {
+                    log.debug("OLAT [regular API call]: URL {}", request.getURI());
+                }
+
                 ClientHttpResponse response = execution.execute(request, body);
-                log.debug("OLAT [regular API call] {} Headers: {}", response.getStatusCode(), response.getHeaders());
+
+                if (log.isDebugEnabled()) {
+                    log.debug("OLAT [regular API call response] {} Headers: {}",
+                            response.getStatusCode(),
+                            response.getHeaders());
+                }
+
                 // If we get a 401, re-authenticate and try once more
-                if (response.getStatusCode() == HttpStatus.UNAUTHORIZED ||
-                      response.getStatusCode() == HttpStatus.FORBIDDEN) {
+                if (response.getStatusCode() == HttpStatus.UNAUTHORIZED
+                /* || response.getStatusCode() == HttpStatus.FORBIDDEN */) {
+
                     authenticate();
                     request.getHeaders().set("X-OLAT-TOKEN", OlatLmsRestTemplate.this.token);
+
+                    if (log.isDebugEnabled()) {
+                        log.debug("OLAT [retry API call]: URL {}", request.getURI());
+                    }
+
                     response = execution.execute(request, body);
-                    log.debug("OLAT [retry API call] {} Headers: {}", response.getStatusCode(), response.getHeaders());
+
+                    if (log.isDebugEnabled()) {
+                        log.debug("OLAT [retry API call response] {} Headers: {}",
+                                response.getStatusCode(),
+                                response.getHeaders());
+                    }
                 }
                 return response;
             }
@@ -76,11 +106,15 @@ public class OlatLmsRestTemplate extends RestTemplate {
         credentials.put("password", this.details.getClientSecret());
         final HttpHeaders httpHeaders = new HttpHeaders();
         httpHeaders.set("content-type", "application/json");
-        final HttpEntity<Map<String,String>> requestEntity = new HttpEntity<>(credentials, httpHeaders);
+        final HttpEntity<Map<String, String>> requestEntity = new HttpEntity<>(credentials, httpHeaders);
         try {
             final ResponseEntity<String> response = this.postForEntity(authUrl, requestEntity, String.class);
             final HttpHeaders responseHeaders = response.getHeaders();
-            log.debug("OLAT [authenticate] {} Headers: {}", response.getStatusCode(), responseHeaders);
+
+            if (log.isDebugEnabled()) {
+                log.debug("OLAT [authenticated] {} Headers: {}", response.getStatusCode(), responseHeaders);
+            }
+
             this.token = responseHeaders.getFirst("X-OLAT-TOKEN");
         } catch (final Exception e) {
             this.token = null;