Error Handling

Error handling

Failures detected while communicating with a compatible website derive from ApiException, while input validation, cancellation, and low-level platform failures use standard .NET exceptions

Library exceptions

Exception	Meaning	Typical response
LoginRequiredException	The requested page requires an authenticated account	Log in and retry with the same client
LoginFailedException	Credentials were rejected or the session could not be verified	Ask for new credentials; do not retry indefinitely
AccountUpdateException	A password or avatar change was rejected	Show the website validation message and keep the previous profile data
CommentOperationException	Comment creation, reply, or deletion was rejected	Check authentication, ownership, moderation, and comment rules
RatingException	An internal rating was rejected	Do not retry an account that has already voted
PremiumRequiredException	Content, a translation, or a quality is Premium-only	Offer an available alternative or require Premium
CaptchaException	The website requested interactive captcha verification	Stop automation and let the user complete verification
StreamFetchException	No usable stream or translator was returned	Try another translation or report temporary unavailability
HttpException	The website returned an unsuccessful HTTP status	Inspect StatusCode; retry only transient statuses
ParseException	Markup, JSON, cookies, compression, or stream data could not be read	Check for a website change and report a reproducible issue

Catch specific failures first

try
{
    using var media = await client.GetAsync(path, cancellationToken);
    var stream = await media.GetStreamAsync(
        cancellationToken: cancellationToken);
}
catch (PremiumRequiredException exception)
{
    Console.WriteLine(
        $"{exception.Feature}: {exception.Name ?? "content"}");
}
catch (CaptchaException)
{
    Console.WriteLine("Interactive verification is required.");
}
catch (HttpException exception)
{
    Console.WriteLine($"HTTP status: {(int)exception.StatusCode}");
}
catch (ParseException exception)
{
    Console.WriteLine($"Website response changed: {exception.Message}");
}
catch (ApiException exception)
{
    Console.WriteLine(exception.Message);
}

Standard exceptions

• ArgumentException — empty input, missing season or episode, unavailable translator, unknown quality, or invalid media path
• ArgumentOutOfRangeException — invalid page, subtitle position, or page limit
• InvalidOperationException — an origin is required, the media format is incompatible with the operation, or request configuration is invalid
• HttpRequestException — DNS, TLS, proxy, socket, or other transport failure
• System.Text.Json.JsonException — malformed JSON returned by a website endpoint
• OperationCanceledException — caller cancellation or a caller-defined timeout

Do not catch OperationCanceledException as a generic failure:

try
{
    return await client.GetAsync(path, cancellationToken);
}
catch (OperationCanceledException)
    when (cancellationToken.IsCancellationRequested)
{
    throw;
}

Retry guidance

Retry only failures likely to be transient, such as selected HTTP 429 or 5xx responses and network interruptions; use bounded retries, exponential backoff, and cancellation, and do not automatically retry invalid input, failed login, Premium requirements, captcha, or a stable parsing failure

GetSeasonStreamsAsync already retries each failed episode once by default See Series and episodes before adding another retry layer around it