1. 首先确认你的API key和RSA Key是否已正确设置，特别是在生产环境中需要注意。也可以尝试在不同的环境中重新设置这些密钥，包括在测试环境和生产环境中使用不同的密钥。

2. 如果以上步骤均无效，可以尝试增加retry逻辑来解决错误520，代码示例如下：

RevenueCatClient client = Purchases.sharedInstance().getRevenueCatClient(); client.addPurchasesUpdatedListener(purchases -> {

final List updatedPurchases = purchases.getPurchasesList();
final List newPurchases = new ArrayList<>();

for (Purchase updatedPurchase : updatedPurchases) {
    if (isRelevantNewPurchase(updatedPurchase)) {
        newPurchases.add(updatedPurchase);
    }
}

if (!newPurchases.isEmpty()) {
    client.postReceipts(newPurchases, new ReceiptPostResponseListener() {
        @Override
        public void onReceived(List postDetails) {
            // TODO handle success
        }

        @Override
        public void onError(Error error) {
            if (error.getCode() == 520) {
                retryReceiptPost(newPurchases, error);
            } else {
                // TODO handle error
            }
        }
    });
}

});

private void retryReceiptPost(List newPurchases, Error error) { // Log the error for debugging Log.e(TAG, "Error " + error.getCode() + " when posting receipts.");

// Retry the post a maximum of 3 times with a 5 second delay in between
int retryCount = 0;
while (retryCount < 3) {
    try {
        Thread.sleep(5000);
    } catch (InterruptedException e) {
        // ignore
    }
    RevenueCatClient client = Purchases.sharedInstance().getRevenueCatClient();
    client.postReceipts(newPurchases, new ReceiptPostResponseListener() {
        @Override
        public void onReceived(List postDetails) {
            // TODO handle success
        }

        @Override
        public void onError(Error error) {