diff --git a/server-mirror-git/src/main/java/com/linecorp/centraldogma/server/internal/mirror/GitMirrorProvider.java b/server-mirror-git/src/main/java/com/linecorp/centraldogma/server/internal/mirror/GitMirrorProvider.java
index 58e362e5c..0d1dd4033 100644
--- a/server-mirror-git/src/main/java/com/linecorp/centraldogma/server/internal/mirror/GitMirrorProvider.java
+++ b/server-mirror-git/src/main/java/com/linecorp/centraldogma/server/internal/mirror/GitMirrorProvider.java
@@ -25,6 +25,10 @@
 
 import java.net.URI;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.linecorp.centraldogma.server.internal.credential.SshKeyCredential;
 import com.linecorp.centraldogma.server.mirror.Mirror;
 import com.linecorp.centraldogma.server.mirror.MirrorContext;
 import com.linecorp.centraldogma.server.mirror.MirrorProvider;
@@ -32,6 +36,8 @@
 
 public final class GitMirrorProvider implements MirrorProvider {
 
+    private static final Logger logger = LoggerFactory.getLogger(GitMirrorProvider.class);
+
     @Override
     public Mirror newMirror(MirrorContext context) {
         requireNonNull(context, "context");
@@ -44,6 +50,10 @@ public Mirror newMirror(MirrorContext context) {
 
         switch (scheme) {
             case SCHEME_GIT_SSH: {
+                if (!(context.credential() instanceof SshKeyCredential)) {
+                    logger.debug("'{}': SSH mirror requires an SSH_KEY credential, " +
+                                "but got: {}", context.id(), context.credential().type());
+                }
                 final RepositoryUri repositoryUri = RepositoryUri.parse(remoteUri, "git");
                 return new SshGitMirror(context.id(), context.enabled(), context.schedule(),
                                         context.direction(), context.credential(),
diff --git a/server-mirror-git/src/main/java/com/linecorp/centraldogma/server/internal/mirror/SshGitMirror.java b/server-mirror-git/src/main/java/com/linecorp/centraldogma/server/internal/mirror/SshGitMirror.java
index 9c9e850b7..d860da71d 100644
--- a/server-mirror-git/src/main/java/com/linecorp/centraldogma/server/internal/mirror/SshGitMirror.java
+++ b/server-mirror-git/src/main/java/com/linecorp/centraldogma/server/internal/mirror/SshGitMirror.java
@@ -101,10 +101,6 @@ final class SshGitMirror extends AbstractGitMirror {
         super(id, enabled, schedule, direction, credential, localRepo, localPath,
               remoteUri, gitignore, zone);
         this.trustedHostKeys = requireNonNull(trustedHostKeys, "trustedHostKeys");
-        if (!(credential instanceof SshKeyCredential)) {
-            throw new MirrorException(
-                    "SSH mirror requires an SSH_KEY credential, but got: " + credential.type());
-        }
     }
 
     @Override
diff --git a/server/src/main/java/com/linecorp/centraldogma/server/internal/storage/repository/DefaultMetaRepository.java b/server/src/main/java/com/linecorp/centraldogma/server/internal/storage/repository/DefaultMetaRepository.java
index 4c87b8bb2..0420809b2 100644
--- a/server/src/main/java/com/linecorp/centraldogma/server/internal/storage/repository/DefaultMetaRepository.java
+++ b/server/src/main/java/com/linecorp/centraldogma/server/internal/storage/repository/DefaultMetaRepository.java
@@ -189,9 +189,9 @@ private CompletableFuture<List<Mirror>> handleAllMirrors(Map<String, Entry<?>> e
                                     } catch (Exception e) {
                                         // Skip a malformed mirror so that a single bad mirror does not
                                         // prevent the rest of the mirrors from being loaded.
-                                        logger.debug("Failed to convert a mirror configuration to a mirror. " +
-                                                     "project: {}, mirror: {}", parent().name(), mirrorConfig,
-                                                     e);
+                                        logger.warn("Failed to convert a mirror configuration to a mirror. " +
+                                                    "project: {}, mirror: {}", parent().name(), mirrorConfig,
+                                                    e);
                                         return null;
                                     }
                                 })