diff --git a/src/main/java/org/italiangrid/storm/webdav/oauth/utils/DefaultOidcConfigurationFetcher.java b/src/main/java/org/italiangrid/storm/webdav/oauth/utils/DefaultOidcConfigurationFetcher.java
index f484a285..4515bf3c 100644
--- a/src/main/java/org/italiangrid/storm/webdav/oauth/utils/DefaultOidcConfigurationFetcher.java
+++ b/src/main/java/org/italiangrid/storm/webdav/oauth/utils/DefaultOidcConfigurationFetcher.java
@@ -21,6 +21,7 @@
 import java.time.Duration;
 import java.util.Arrays;
 import java.util.Map;
+import java.util.Objects;
 
 import org.italiangrid.storm.webdav.config.OAuthProperties;
 import org.slf4j.Logger;
@@ -99,6 +100,9 @@ public Map<String, Object> loadConfigurationForIssuer(String issuer) {
       throw new OidcConfigurationResolutionError(
           format("Received status code: %s", response.getStatusCodeValue()));
     }
+    if (Objects.isNull(response.getBody())) {
+      throw new OidcConfigurationResolutionError("Received null body");
+    }
     metadataChecks(issuer, response.getBody());
     return response.getBody();
   }
diff --git a/src/main/java/org/italiangrid/storm/webdav/oauth/utils/NoExpirationStringCache.java b/src/main/java/org/italiangrid/storm/webdav/oauth/utils/NoExpirationStringCache.java
index 7f7a70ee..4bc9e253 100644
--- a/src/main/java/org/italiangrid/storm/webdav/oauth/utils/NoExpirationStringCache.java
+++ b/src/main/java/org/italiangrid/storm/webdav/oauth/utils/NoExpirationStringCache.java
@@ -43,19 +43,22 @@ public Object getNativeCache() {
   @Override
   @Nullable
   protected Object lookup(Object key) {
-      return value;
+    return value;
   }
 
   @Override
   public void put(Object key, Object value) {
+    // Nothing to do
   }
 
   @Override
   public void evict(Object key) {
+    // Nothing to do
   }
 
   @Override
   public void clear() {
+    // Nothing to do
   }
 
   @SuppressWarnings("unchecked")
@@ -63,4 +66,4 @@ public void clear() {
   public <T> T get(Object key, Callable<T> valueLoader) {
     return (T) fromStoreValue(value);
   }
-}
\ No newline at end of file
+}
diff --git a/src/test/java/org/italiangrid/storm/webdav/server/TLSConnectorBuilderTest.java b/src/test/java/org/italiangrid/storm/webdav/server/TLSConnectorBuilderTest.java
index 70bbcb27..b7fcbba9 100644
--- a/src/test/java/org/italiangrid/storm/webdav/server/TLSConnectorBuilderTest.java
+++ b/src/test/java/org/italiangrid/storm/webdav/server/TLSConnectorBuilderTest.java
@@ -41,7 +41,7 @@
 import eu.emi.security.authn.x509.X509CertChainValidatorExt;
 
 @ExtendWith(MockitoExtension.class)
-public class TLSConnectorBuilderTest {
+class TLSConnectorBuilderTest {
 
   @Test
   void tlsConnectorBuilderErrorTests() {
diff --git a/src/test/java/org/italiangrid/storm/webdav/test/oauth/jwk/OidcConfigurationFetcherTest.java b/src/test/java/org/italiangrid/storm/webdav/test/oauth/jwk/OidcConfigurationFetcherTest.java
index 5b8162ea..8630609b 100644
--- a/src/test/java/org/italiangrid/storm/webdav/test/oauth/jwk/OidcConfigurationFetcherTest.java
+++ b/src/test/java/org/italiangrid/storm/webdav/test/oauth/jwk/OidcConfigurationFetcherTest.java
@@ -55,6 +55,7 @@
 
 import com.google.common.collect.Maps;
 import com.nimbusds.jose.KeySourceException;
+import com.nimbusds.jose.RemoteKeySourceException;
 import com.nimbusds.jose.jwk.JWKSet;
 import com.nimbusds.jose.jwk.KeyType;
 
@@ -62,7 +63,7 @@
 class OidcConfigurationFetcherTest {
 
   static final String ISSUER = "https://iam-dev.cloud.cnaf.infn.it/";
-  final static String JWK_URI = ISSUER + "jwk";
+  static final String JWK_URI = ISSUER + "jwk";
 
   static final String ANOTHER_ISSUER = "https://iam.cloud.infn.it/";
   static final String ANOTHER_JWK_URI = ANOTHER_ISSUER + "jwk";
@@ -122,6 +123,18 @@ private OidcConfigurationFetcher getFetcher(ResponseEntity<Map<String, Object>>
 
     lenient().when(restTemplate.exchange(any(), eq(typeReference))).thenReturn(wellKnownResponse);
     lenient().when(restTemplate.exchange(any(), eq(String.class))).thenReturn(jwkResponse);
+    return getFetcher(restTemplate);
+  }
+
+  private OidcConfigurationFetcher getFetcherWithException(ResponseEntity<Map<String, Object>> wellKnownResponse) {
+
+    lenient().when(restTemplate.exchange(any(), eq(typeReference))).thenReturn(wellKnownResponse);
+    lenient().when(restTemplate.exchange(any(), eq(String.class))).thenThrow(new RuntimeException("ERROR"));
+    return getFetcher(restTemplate);
+  }
+
+  private OidcConfigurationFetcher getFetcher(RestTemplate restTemplate) {
+
     lenient().when(restBuilder.build()).thenReturn(restTemplate);
     lenient().when(restBuilder.setConnectTimeout(any())).thenReturn(restBuilder);
     lenient().when(restBuilder.setReadTimeout(any())).thenReturn(restBuilder);
@@ -174,8 +187,7 @@ private OidcConfigurationFetcher getFetcherWithErrorOnFetch() throws RestClientE
     return getFetcher(mockedResponseMapEntity, null);
   }
 
-  private OidcConfigurationFetcher getFetcherWithErrorOnGetJwk()
-      throws RestClientException, IOException {
+  private OidcConfigurationFetcher getFetcherWithErrorOnGetJwk() throws RestClientException {
 
     ResponseEntity<Map<String, Object>> mockedResponseMapEntity =
         getWellKnownResponse(OK, getMapWithIssuerAndJwkUri(ISSUER, JWK_URI));
@@ -183,6 +195,13 @@ private OidcConfigurationFetcher getFetcherWithErrorOnGetJwk()
     return getFetcher(mockedResponseMapEntity, mockedResponseStringEntity);
   }
 
+  private OidcConfigurationFetcher getFetcherWithRuntimeExceptionOnGetJwk() throws RestClientException {
+
+    ResponseEntity<Map<String, Object>> mockedResponseMapEntity =
+        getWellKnownResponse(OK, getMapWithIssuerAndJwkUri(ISSUER, JWK_URI));
+    return getFetcherWithException(mockedResponseMapEntity);
+  }
+
   @BeforeEach
   public void setDebugLevel() {
     System.setProperty("logging.level.org.italiangrid.storm", "DEBUG");
@@ -199,7 +218,7 @@ void fetchWellKnownEndpointWithSuccessTests() throws RestClientException, IOExce
   }
 
   @Test
-  void fetchWellKnownEndpointWithErrorTests() throws RestClientException, IOException {
+  void fetchWellKnownEndpointWithErrorTests() throws RestClientException {
 
     OidcConfigurationFetcher fetcher = getFetcherWithErrorOnFetch();
     RuntimeException exception = assertThrows(RuntimeException.class, () -> {
@@ -271,4 +290,18 @@ void fetchJWKEndpointWithErrorTests() throws RestClientException, IOException {
 
     assertEquals(expectedMessage, actualMessage);
   }
+
+  @Test
+  void fetchJWKEndpointWithRuntimeException() throws RestClientException, IOException {
+
+    OidcConfigurationFetcher fetcher = getFetcherWithRuntimeExceptionOnGetJwk();
+    final URI jwkUri = URI.create(JWK_URI);
+    RemoteKeySourceException exception = assertThrows(RemoteKeySourceException.class, () -> {
+      fetcher.loadJWKSourceForURL(jwkUri);
+    });
+    String expectedMessage = "Unable to get JWK from 'https://iam-dev.cloud.cnaf.infn.it/jwk'";
+    String actualMessage = exception.getMessage();
+
+    assertEquals(expectedMessage, actualMessage);
+  }
 }