nopSolutions/nopCommerce · error · NopException

No response from the service

Error message

No response from the service

What it means

CreateTransaction calls ServiceClient.CreateTransaction(null, model) to compute or commit a tax transaction. The Avalara AvaTax REST client returned null instead of a TransactionModel, so the plugin throws because no tax data means the order's tax cannot be determined safely. This is the core tax-calculation entry point; a null here blocks checkout/invoice pricing.

Source

Thrown at src/Plugins/Nop.Plugin.Tax.Avalara/Services/AvalaraTaxManager.cs:230

            await _logger.ErrorAsync($"{AvalaraTaxDefaults.SystemName} error. {errorMessage}", exception, await _workContext.GetCurrentCustomerAsync());

            return (default, errorMessage);
        }
    }

    #endregion

    #region Tax calculation

    /// <summary>
    /// Create tax transaction
    /// </summary>
    /// <param name="model">Transaction details</param>
    /// <returns>Created transaction</returns>
    protected TransactionModel CreateTransaction(CreateTransactionModel model)
    {
        var transaction = ServiceClient.CreateTransaction(null, model)
            ?? throw new NopException("No response from the service");

        //whether there are any errors
        var errors = transaction.messages?.Where(m => !m.severity?.ToLower().Equals("success") ?? true).ToList() ?? [];

        if (!errors.Any())
            return transaction;

        var message = errors.Aggregate(string.Empty, (error, message) => $"{error}{message.summary}{Environment.NewLine}");
        throw new NopException(message);
    }

    /// <summary>
    /// Prepare model to create a tax transaction
    /// </summary>
    /// <param name="address">Tax address</param>
    /// <param name="customerCode">Customer code</param>
    /// <param name="documentType">Transaction document type</param>
    /// <returns>

View on GitHub (pinned to 64bdf2ff08)

Solutions

1. Verify AccountId and LicenseKey in the Avalara tax provider settings and confirm Sandbox/Production matches the account type.
2. Inspect the TaxTransactionLog (written by OnCallCompleted) for the actual HTTP status code and response body of the failed CreateTransaction call.
3. Ensure no proxy/firewall rewrites or strips the JSON response, and that rest.avatax.com is reachable.
4. Validate the CreateTransactionModel before sending: non-empty companyCode, valid date, at least one line with a taxCode, and a resolved address.
5. Upgrade the Avalara.AvaTax.RestClient NuGet package to the latest version compatible with the plugin.

Example fix

// before
var transaction = ServiceClient.CreateTransaction(null, model)
    ?? throw new NopException("No response from the service");

// after - log diagnostics and point to the transaction log
var transaction = ServiceClient.CreateTransaction(null, model);
if (transaction is null)
{
    await _logger.ErrorAsync($"Avalara CreateTransaction returned null for company '{model?.companyCode}'. Check TaxTransactionLog for HTTP status.");
    throw new NopException("No response from the service (see TaxTransactionLog)");
}

// Validate config and model before the call
if (string.IsNullOrEmpty(_avalaraTaxSettings.AccountId) || string.IsNullOrEmpty(_avalaraTaxSettings.LicenseKey))
    throw new NopException("Tax provider is not configured");
if (model is null || string.IsNullOrEmpty(model.companyCode) || model.date == default)
    throw new NopException("Invalid transaction model");

// CreateTransaction throws NopException on null or aggregated errors;
// wrap it so callers degrade gracefully (matches HandleFunctionAsync)
try
{
    var tx = CreateTransaction(model);
    return tx;
}
catch (NopException ex)
{
    await _logger.ErrorAsync($"Avalara CreateTransaction failed: {ex.Message}", ex, await _workContext.GetCurrentCustomerAsync());
    return null;
}

When it happens

Trigger: ServiceClient.CreateTransaction(null, model) returns null. This happens when the AvaTax client receives a response it cannot deserialize into TransactionModel (empty body, HTML error page from a proxy, or an auth redirect) while the HTTP layer did not raise an AvaTaxError. A null is distinct from an AvaTaxError exception, which carries structured error info.

Common situations: Invalid or expired AccountId/LicenseKey producing a non-JSON 401/403; corporate proxy returning an HTML challenge page; Sandbox vs Production URL mismatch for the account; a malformed CreateTransactionModel (empty companyCode, missing/future date, null lines) that Avalara rejects in a way the client surfaces as null; an outdated Avalara.AvaTax.RestClient package.

Related errors

• {aggregated error summaries}
• Failed to delete customer
• Failed to get customer's certificates
• Failed to download certificate
• Failed to get invitation

AI-assisted analysis of nopSolutions/nopCommerce@64bdf2ff08 (2026-08-13). Data as JSON: /api/errors/143dd8b771d35c56. Report an issue: GitHub.