diff --git a/src/lib/docker-utils.ts b/src/lib/docker-utils.ts
index 3d699d02..3018a3e6 100644
--- a/src/lib/docker-utils.ts
+++ b/src/lib/docker-utils.ts
@@ -109,7 +109,7 @@ export class DockerUtils extends DockerToolbelt {
 		const token = tokenResponseBody != null ? tokenResponseBody.token : null;
 
 		if (token == null) {
-			throw new ImageAuthenticationError();
+			throw new ImageAuthenticationError('Authentication error');
 		}
 
 		const opts: requestLib.CoreOptions = {
diff --git a/src/logger.ts b/src/logger.ts
index d2b6e7db..c81d2551 100644
--- a/src/logger.ts
+++ b/src/logger.ts
@@ -162,7 +162,8 @@ export class Logger {
 		if (obj && obj.error != null) {
 			let errorMessage = obj.error.message;
 			if (_.isEmpty(errorMessage)) {
-				errorMessage = 'Unknown cause';
+				errorMessage =
+					obj.error.name !== 'Error' ? obj.error.name : 'Unknown cause';
 				console.error('Warning: invalid error message', obj.error);
 			}
 			message += ` due to '${errorMessage}'`;