diff --git a/src/main/java/com/apple/itunes/storekit/client/APIError.java b/src/main/java/com/apple/itunes/storekit/client/APIError.java
index 8d284306..e97ffd12 100644
--- a/src/main/java/com/apple/itunes/storekit/client/APIError.java
+++ b/src/main/java/com/apple/itunes/storekit/client/APIError.java
@@ -10,60 +10,390 @@
  * See the specific documentation for each endpoint to learn more about what codes are possible from each endpoint.
  */
 public enum APIError {
+    /**
+     * An error that indicates an invalid request.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/generalbadrequesterror">GeneralBadRequestError</a>
+     */
     GENERAL_BAD_REQUEST(4000000L),
+
+    /**
+     * An error that indicates an invalid app identifier.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidappidentifiererror">InvalidAppIdentifierError</a>
+     */
     INVALID_APP_IDENTIFIER(4000002L),
+
+    /**
+     * An error that indicates an invalid request revision.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidrequestrevisionerror">InvalidRequestRevisionError</a>
+     */
     INVALID_REQUEST_REVISION(4000005L),
+
+    /**
+     * An error that indicates an invalid transaction identifier.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidtransactioniderror">InvalidTransactionIdError</a>
+     */
     INVALID_TRANSACTION_ID(4000006L),
+
+    /**
+     * An error that indicates an invalid original transaction identifier.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidoriginaltransactioniderror">InvalidOriginalTransactionIdError</a>
+     */
     INVALID_ORIGINAL_TRANSACTION_ID(4000008L),
+
+    /**
+     * An error that indicates an invalid extend-by-days value.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidextendbydayserror">InvalidExtendByDaysError</a>
+     */
     INVALID_EXTEND_BY_DAYS(4000009L),
+
+    /**
+     * An error that indicates an invalid reason code.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidextendreasoncodeerror">InvalidExtendReasonCodeError</a>
+     */
     INVALID_EXTEND_REASON_CODE(4000010L),
-    INVALID_IDENTIFIER(4000011L),
+
+    /**
+     * An error that indicates an invalid request identifier.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidrequestidentifiererror">InvalidRequestIdentifierError</a>
+     */
+    INVALID_REQUEST_IDENTIFIER(4000011L),
+
+    /**
+     * An error that indicates that the start date is earlier than the earliest allowed date.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/startdatetoofarinpasterror">StartDateTooFarInPastError</a>
+     */
     START_DATE_TOO_FAR_IN_PAST(4000012L),
+
+    /**
+     * An error that indicates that the end date precedes the start date, or the two dates are equal.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/startdateafterenddateerror">StartDateAfterEndDateError</a>
+     */
     START_DATE_AFTER_END_DATE(4000013L),
+
+    /**
+     * An error that indicates the pagination token is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidpaginationtokenerror">InvalidPaginationTokenError</a>
+     */
     INVALID_PAGINATION_TOKEN(4000014L),
+
+    /**
+     * An error that indicates the start date is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidstartdateerror">InvalidStartDateError</a>
+     */
     INVALID_START_DATE(4000015L),
+
+    /**
+     * An error that indicates the end date is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidenddateerror">InvalidEndDateError</a>
+     */
     INVALID_END_DATE(4000016L),
+
+    /**
+     * An error that indicates the pagination token expired.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/paginationtokenexpirederror">PaginationTokenExpiredError</a>
+     */
     PAGINATION_TOKEN_EXPIRED(4000017L),
+
+    /**
+     * An error that indicates the notification type or subtype is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidnotificationtypeerror">InvalidNotificationTypeError</a>
+     */
     INVALID_NOTIFICATION_TYPE(4000018L),
+
+    /**
+     * An error that indicates the request is invalid because it has too many constraints applied.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/multiplefilterssuppliederror">MultipleFiltersSuppliedError</a>
+     */
     MULTIPLE_FILTERS_SUPPLIED(4000019L),
+
+    /**
+     * An error that indicates the test notification token is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidtestnotificationtokenerror">InvalidTestNotificationTokenError</a>
+     */
     INVALID_TEST_NOTIFICATION_TOKEN(4000020L),
+
+    /**
+     * An error that indicates an invalid sort parameter.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidsorterror">InvalidSortError</a>
+     */
     INVALID_SORT(4000021L),
+
+    /**
+     * An error that indicates an invalid product type parameter.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidproducttypeerror">InvalidProductTypeError</a>
+     */
     INVALID_PRODUCT_TYPE(4000022L),
+
+    /**
+     * An error that indicates the product ID parameter is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidproductiderror">InvalidProductIdError</a>
+     */
     INVALID_PRODUCT_ID(4000023L),
+
+    /**
+     * An error that indicates an invalid subscription group identifier.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidsubscriptiongroupidentifiererror">InvalidSubscriptionGroupIdentifierError</a>
+     */
     INVALID_SUBSCRIPTION_GROUP_IDENTIFIER(4000024L),
+
+    /**
+     * An error that indicates the query parameter exclude-revoked is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidexcluderevokederror">InvalidExcludeRevokedError</a>
+     */
+    @Deprecated
     INVALID_EXCLUDE_REVOKED(4000025L),
+
+    /**
+     * An error that indicates an invalid in-app ownership type parameter.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidinappownershiptypeerror">InvalidInAppOwnershipTypeError</a>
+     */
     INVALID_IN_APP_OWNERSHIP_TYPE(4000026L),
+
+    /**
+     * An error that indicates a required storefront country code is empty.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidemptystorefrontcountrycodelisterror">InvalidEmptyStorefrontCountryCodeListError</a>
+     */
     INVALID_EMPTY_STOREFRONT_COUNTRY_CODE_LIST(4000027L),
+
+    /**
+     * An error that indicates a storefront code is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidstorefrontcountrycodeerror">InvalidStorefrontCountryCodeError</a>
+     */
     INVALID_STOREFRONT_COUNTRY_CODE(4000028L),
+
+    /**
+     * An error that indicates the revoked parameter contains an invalid value.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidrevokederror">InvalidRevokedError</a>
+     */
     INVALID_REVOKED(4000030L),
+
+    /**
+     * An error that indicates the status parameter is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidstatuserror">InvalidStatusError</a>
+     */
     INVALID_STATUS(4000031L),
+
+    /**
+     * An error that indicates the value of the account tenure field is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidaccounttenureerror">InvalidAccountTenureError</a>
+     */
     INVALID_ACCOUNT_TENURE(4000032L),
+
+    /**
+     * An error that indicates the value of the app account token field is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidappaccounttokenerror">InvalidAppAccountTokenError</a>
+     */
     INVALID_APP_ACCOUNT_TOKEN(4000033L),
+
+    /**
+     * An error that indicates the value of the consumption status field is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidconsumptionstatuserror">InvalidConsumptionStatusError</a>
+     */
     INVALID_CONSUMPTION_STATUS(4000034L),
+
+    /**
+     * An error that indicates the customer consented field is invalid or doesn’t indicate that the customer consented.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidcustomerconsentederror">InvalidCustomerConsentedError</a>
+     */
     INVALID_CUSTOMER_CONSENTED(4000035L),
+
+    /**
+     * An error that indicates the value in the delivery status field is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invaliddeliverystatuserror">InvalidDeliveryStatusError</a>
+     */
     INVALID_DELIVERY_STATUS(4000036L),
+
+    /**
+     * An error that indicates the value in the lifetime dollars purchased field is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidlifetimedollarspurchasederror">InvalidLifetimeDollarsPurchasedError</a>
+     */
     INVALID_LIFETIME_DOLLARS_PURCHASED(4000037L),
+
+    /**
+     * An error that indicates the value in the lifetime dollars refunded field is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidlifetimedollarsrefundederror">InvalidLifetimeDollarsRefundedError</a>
+     */
     INVALID_LIFETIME_DOLLARS_REFUNDED(4000038L),
+
+    /**
+     * An error that indicates the value in the platform field is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidplatformerror">InvalidPlatformError</a>
+     */
     INVALID_PLATFORM(4000039L),
+
+    /**
+     * An error that indicates the value in the playtime field is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidplaytimeerror">InvalidPlayTimeError</a>
+     */
     INVALID_PLAY_TIME(4000040L),
+
+    /**
+     * An error that indicates the value in the sample content provided field is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidsamplecontentprovidederror">InvalidSampleContentProvidedError</a>
+     */
     INVALID_SAMPLE_CONTENT_PROVIDED(4000041L),
+
+    /**
+     * An error that indicates the value in the user status field is invalid.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invaliduserstatuserror">InvalidUserStatusError</a>
+     */
     INVALID_USER_STATUS(4000042L),
+
+    /**
+     * An error that indicates the transaction identifier doesn’t represent a consumable in-app purchase.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/invalidtransactionnotconsumableerror">InvalidTransactionNotConsumableError</a>
+     */
     INVALID_TRANSACTION_NOT_CONSUMABLE(4000043L),
+
+    /**
+     * An error that indicates the subscription doesn't qualify for a renewal-date extension due to its subscription state.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/subscriptionextensionineligibleerror">SubscriptionExtensionIneligibleError</a>
+     */
     SUBSCRIPTION_EXTENSION_INELIGIBLE(4030004L),
+
+    /**
+     * An error that indicates the subscription doesn’t qualify for a renewal-date extension because it has already received the maximum extensions.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/subscriptionmaxextensionerror">SubscriptionMaxExtensionError</a>
+     */
     SUBSCRIPTION_MAX_EXTENSION(4030005L),
+
+    /**
+     * An error that indicates a subscription isn't directly eligible for a renewal date extension because the user obtained it through Family Sharing.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/familysharedsubscriptionextensionineligibleerror">FamilySharedSubscriptionExtensionIneligibleError</a>
+     */
     FAMILY_SHARED_SUBSCRIPTION_EXTENSION_INELIGIBLE(4030007L),
+
+    /**
+     * An error that indicates the App Store account wasn’t found.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/accountnotfounderror">AccountNotFoundError</a>
+     */
     ACCOUNT_NOT_FOUND(4040001L),
+
+    /**
+     * An error response that indicates the App Store account wasn’t found, but you can try again.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/accountnotfoundretryableerror">AccountNotFoundRetryableError</a>
+     */
     ACCOUNT_NOT_FOUND_RETRYABLE(4040002L),
+
+    /**
+     * An error that indicates the app wasn’t found.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/appnotfounderror">AppNotFoundError</a>
+     */
     APP_NOT_FOUND(4040003L),
+
+    /**
+     * An error response that indicates the app wasn’t found, but you can try again.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/appnotfoundretryableerror">AppNotFoundRetryableError</a>
+     */
     APP_NOT_FOUND_RETRYABLE(4040004L),
+
+    /**
+     * An error that indicates an original transaction identifier wasn't found.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/originaltransactionidnotfounderror">OriginalTransactionIdNotFoundError</a>
+     */
     ORIGINAL_TRANSACTION_ID_NOT_FOUND(4040005L),
+
+    /**
+     * An error response that indicates the original transaction identifier wasn’t found, but you can try again.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/originaltransactionidnotfoundretryableerror">OriginalTransactionIdNotFoundRetryableError</a>
+     */
     ORIGINAL_TRANSACTION_ID_NOT_FOUND_RETRYABLE(4040006L),
+
+    /**
+     * An error that indicates that the App Store server couldn’t find a notifications URL for your app in this environment.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/servernotificationurlnotfounderror">ServerNotificationUrlNotFoundError</a>
+     */
     SERVER_NOTIFICATION_URL_NOT_FOUND(4040007L),
+
+    /**
+     * An error that indicates that the test notification token is expired or the test notification status isn’t available.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/testnotificationnotfounderror">TestNotificationNotFoundError</a>
+     */
     TEST_NOTIFICATION_NOT_FOUND(4040008L),
+
+    /**
+     * An error that indicates the server didn't find a subscription-renewal-date extension request for the request identifier and product identifier you provided.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/statusrequestnotfounderror">StatusRequestNotFoundError</a>
+     */
     STATUS_REQUEST_NOT_FOUND(4040009L),
+
+    /**
+     * An error that indicates a transaction identifier wasn't found.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/transactionidnotfounderror">TransactionIdNotFoundError</a>
+     */
     TRANSACTION_ID_NOT_FOUND(4040010L),
+
+    /**
+     * An error that indicates that the request exceeded the rate limit.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/ratelimitexceedederror">RateLimitExceededError</a>
+     */
     RATE_LIMIT_EXCEEDED(4290000L),
+
+    /**
+     * An error that indicates a general internal error.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/generalinternalerror">GeneralInternalError</a>
+     */
     GENERAL_INTERNAL(5000000L),
+
+    /**
+     * An error response that indicates an unknown error occurred, but you can try again.
+     *
+     * @see <a href="https://developer.apple.com/documentation/appstoreserverapi/generalinternalretryableerror">GeneralInternalRetryableError</a>
+     */
     GENERAL_INTERNAL_RETRYABLE(5000001L);
 
     private final long errorCode;
diff --git a/src/main/java/com/apple/itunes/storekit/client/APIException.java b/src/main/java/com/apple/itunes/storekit/client/APIException.java
index cb97f695..4d227ad2 100644
--- a/src/main/java/com/apple/itunes/storekit/client/APIException.java
+++ b/src/main/java/com/apple/itunes/storekit/client/APIException.java
@@ -9,21 +9,35 @@
  */
 public class APIException extends Exception {
     private final int httpStatusCode;
-    private final Long apiError;
+    private final Long apiErrorCode;
+    private final String apiErrorMessage;
+
+    public APIException(int httpStatusCode, Exception cause) {
+        super("Failed to call API with httpStatusCode=" + httpStatusCode, cause);
+        this.httpStatusCode = httpStatusCode;
+        this.apiErrorCode = null;
+        this.apiErrorMessage = null;
+    }
 
     public APIException(int httpStatusCode) {
+        super("Failed to call API with httpStatusCode=" + httpStatusCode);
         this.httpStatusCode = httpStatusCode;
-        this.apiError = null;
+        this.apiErrorCode = null;
+        this.apiErrorMessage = null;
     }
 
-    public APIException(int httpStatusCode, APIError apiError) {
+    public APIException(int httpStatusCode, APIError apiError, String apiErrorMessage) {
+        super("Failed to call API with error=\"" + apiErrorMessage + "\"");
         this.httpStatusCode = httpStatusCode;
-        this.apiError = apiError != null ? apiError.errorCode() : null;
+        this.apiErrorCode = apiError != null ? apiError.errorCode() : null;
+        this.apiErrorMessage = apiErrorMessage;
     }
 
-    public APIException(int httpStatusCode, Long rawApiError) {
+    public APIException(int httpStatusCode, Long rawApiError, String apiErrorMessage) {
+        super("Failed to call API with error=\"" + apiErrorMessage + "\"");
         this.httpStatusCode = httpStatusCode;
-        this.apiError = rawApiError;
+        this.apiErrorCode = rawApiError;
+        this.apiErrorMessage = apiErrorMessage;
     }
 
     public int getHttpStatusCode() {
@@ -31,18 +45,23 @@ public int getHttpStatusCode() {
     }
 
     public APIError getApiError() {
-        return apiError != null ? APIError.fetchErrorResponseFromErrorCode(apiError) : null;
+        return apiErrorCode != null ? APIError.fetchErrorResponseFromErrorCode(apiErrorCode) : null;
     }
 
     public Long getRawApiError() {
-        return apiError;
+        return apiErrorCode;
+    }
+
+    public String getApiErrorMessage() {
+        return apiErrorMessage;
     }
 
     @Override
     public String toString() {
         return "APIException{" +
                 "httpStatusCode=" + httpStatusCode +
-                ", apiError=" + apiError +
-                "} " + super.toString();
+                ", apiError=" + apiErrorCode +
+                ", apiErrorMessage='" + apiErrorMessage + '\'' +
+                '}';
     }
 }
diff --git a/src/main/java/com/apple/itunes/storekit/client/AppStoreServerAPIClient.java b/src/main/java/com/apple/itunes/storekit/client/AppStoreServerAPIClient.java
index 0b2d203d..681c556f 100644
--- a/src/main/java/com/apple/itunes/storekit/client/AppStoreServerAPIClient.java
+++ b/src/main/java/com/apple/itunes/storekit/client/AppStoreServerAPIClient.java
@@ -115,10 +115,8 @@ protected <T> T makeHttpCall(String path, String method, Map<String, List<String
                 }
                 try {
                     return objectMapper.readValue(responseBody.charStream(), clazz);
-                } catch (JsonProcessingException suppressed) {
-                    APIException e = new APIException(r.code());
-                    e.addSuppressed(suppressed);
-                    throw e;
+                } catch (JsonProcessingException e) {
+                    throw new APIException(r.code(), e);
                 }
             } else {
                 // Best effort to decode the body
@@ -126,14 +124,12 @@ protected <T> T makeHttpCall(String path, String method, Map<String, List<String
                     ResponseBody responseBody = r.body();
                     if (responseBody != null) {
                         ErrorPayload errorPayload = objectMapper.readValue(responseBody.charStream(), ErrorPayload.class);
-                        throw new APIException(r.code(), errorPayload.getErrorCode());
+                        throw new APIException(r.code(), errorPayload.getErrorCode(), errorPayload.getErrorMessage());
                     }
                 } catch (APIException e) {
                     throw e;
-                } catch (Exception suppressed) {
-                    APIException e = new APIException(r.code());
-                    e.addSuppressed(suppressed);
-                    throw e;
+                } catch (Exception e) {
+                    throw new APIException(r.code(), e);
                 }
                 throw new APIException(r.code());
             }
diff --git a/src/test/java/com/apple/itunes/storekit/client/AppStoreServerAPIClientTest.java b/src/test/java/com/apple/itunes/storekit/client/AppStoreServerAPIClientTest.java
index 50172970..d28b503e 100644
--- a/src/test/java/com/apple/itunes/storekit/client/AppStoreServerAPIClientTest.java
+++ b/src/test/java/com/apple/itunes/storekit/client/AppStoreServerAPIClientTest.java
@@ -475,6 +475,7 @@ public void testAPIError() throws IOException {
             Assertions.assertEquals(500, e.getHttpStatusCode());
             Assertions.assertEquals(APIError.GENERAL_INTERNAL, e.getApiError());
             Assertions.assertEquals(5000000L, e.getRawApiError());
+            Assertions.assertEquals("An unknown error occurred.", e.getApiErrorMessage());
             return;
         }
         Assertions.fail();
@@ -490,6 +491,7 @@ public void testAPITooManyRequests() throws IOException {
             Assertions.assertEquals(429, e.getHttpStatusCode());
             Assertions.assertEquals(APIError.RATE_LIMIT_EXCEEDED, e.getApiError());
             Assertions.assertEquals(4290000L, e.getRawApiError());
+            Assertions.assertEquals("Rate limit exceeded.", e.getApiErrorMessage());
             return;
         }
         Assertions.fail();
@@ -505,6 +507,7 @@ public void testAPIUnknownError() throws IOException {
             Assertions.assertEquals(400, e.getHttpStatusCode());
             Assertions.assertNull(e.getApiError());
             Assertions.assertEquals(9990000L, e.getRawApiError());
+            Assertions.assertEquals("Testing error.", e.getApiErrorMessage());
             return;
         }
         Assertions.fail();
@@ -549,6 +552,11 @@ public void testDecodingWithMalformedJson() throws IOException {
         try {
             client.getTransactionHistory("1234", "revision_input", request);
         } catch (APIException e) {
+            Assertions.assertNull(e.getApiErrorMessage());
+            Assertions.assertNull(e.getApiError());
+            Assertions.assertNull(e.getRawApiError());
+            Assertions.assertEquals(200, e.getHttpStatusCode());
+            Assertions.assertNotNull(e.getCause());
             return;
         }
         Assertions.fail();