microsoft/semantic-kernel · error · NotSupportedException

The provided response modalities '{modalityString}' is not s

Error message

The provided response modalities '{modalityString}' is not supported.

What it means

Thrown inside GetResponseModalities (ParseResponseModalitiesEnumerable) when executionSettings.Modalities is an IEnumerable<string> and one element cannot be parsed into the ChatResponseModalities flags enum (case-insensitive Enum.TryParse fails). Each unrecognized modality string triggers this before the rest are processed.

Source

Thrown at dotnet/src/Connectors/Connectors.AzureOpenAI/Core/AzureClientCore.ChatCompletion.cs:157

    /// <summary>
    /// Gets the response modalities from the execution settings.
    /// </summary>
    /// <param name="executionSettings">The execution settings.</param>
    /// <returns>The response modalities as a <see cref="ChatResponseModalities"/> flags enum.</returns>
    private static ChatResponseModalities GetResponseModalities(OpenAIPromptExecutionSettings executionSettings)
    {
        static ChatResponseModalities ParseResponseModalitiesEnumerable(IEnumerable<string> responseModalitiesStrings)
        {
            ChatResponseModalities result = ChatResponseModalities.Default;
            foreach (var modalityString in responseModalitiesStrings)
            {
                if (Enum.TryParse<ChatResponseModalities>(modalityString, true, out var parsedModality))
                {
                    result |= parsedModality;
                }
                else
                {
                    throw new NotSupportedException($"The provided response modalities '{modalityString}' is not supported.");
                }
            }

            return result;
        }

        if (executionSettings.Modalities is null)
        {
            return ChatResponseModalities.Default;
        }

        if (executionSettings.Modalities is ChatResponseModalities responseModalities)
        {
            return responseModalities;
        }

        if (executionSettings.Modalities is IEnumerable<string> responseModalitiesStrings)
        {

View on GitHub (pinned to c028a0c7dc)

Solutions

Use only valid ChatResponseModalities names: 'Text', 'Audio', 'Image' (and 'Default'); verify the enum members for your package version.
Validate each modality string against the enum before assigning Modalities.
Load modalities from config via a strongly typed list and reject unknown values early.

Example fix

// before
settings.Modalities = new List<string> { "Text", "Video" };
// throws: The provided response modalities 'Video' is not supported.

// after
settings.Modalities = new List<string> { "Text", "Audio" };

Defensive patterns

Strategy: validation

Validate before calling

static readonly HashSet<string> s_modalities = Enum.GetNames<ChatResponseModalities>().ToHashSet(StringComparer.OrdinalIgnoreCase);

bool ValidateModalities(IEnumerable<string> mods) => mods.All(m => s_modalities.Contains(m));

Type guard

bool AreValidModalities(IEnumerable<string> mods)
    => mods.All(m => Enum.TryParse<ChatResponseModalities>(m, true, out _));

Try / catch

try { /* kernel call with Modalities = new[] { "Text", "Audio" } */ }
catch (NotSupportedException ex) when (ex.Message.Contains("response modalities"))
{ throw new ConfigurationException($"Invalid response modalities. Valid names: {string.Join(", ", Enum.GetNames<ChatResponseModalities>())}.", ex); }

Prevention

Restrict modality strings to ChatResponseModalities enum member names (Text, Audio, Image, Default).
Validate loaded modalities against the enum before assigning Modalities.
Document the accepted modality names next to config schema.

When it happens

Trigger: Setting Modalities to a string collection containing a value that is not a member of Azure.AI.OpenAI.Chat.ChatResponseModalities — e.g. new[] { "Text", "Video" } (Video is not a valid member), or a typo like new[] { "txt" }, or new[] { "text", "audoi" }.

Common situations: Loading modalities from config with a misspelled or unsupported modality name. Assuming 'video', 'image-generation', or other non-enum names are accepted. Copying modality strings from a different provider's docs.

Related errors

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/bbbf55b43e845df6. Report an issue: GitHub.