Bad Request when using C# XML comment completion

[KuroiLight]

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Having a issue when trying to generate C# xml summaries (<summary>)
e.g. typing /// causes the [...] to appear for a second then I get the error below.
I tried:

• resetting VisualStudio
• signing out then in on all accounts (github/microsoft)
• running visual studio repair
• deleting copilot cache files
• changing ',' to '.' in number format settings(it was already '.')
• creating new console solution, still not working.

[CopilotSessionProvider Information] Begin sending message (ConversationId:dba87326-a50e-4f3d-b71f-b0acb5c00bd0, CorrelationId:44747c0a-6ad5-4f46-bf66-a9fbc412f145, MessageId: 32e6186e-3327-4925-8139-9703cb36a116)
[CopilotSessionProvider Information] Request content: "You are an AI assistant tasked with generating **C# XML documentation comments** for code elements
(classes, methods, properties, etc.). Follow **.NET best practices** from Microsoft's documentation
(learn.microsoft.com and/or docs.microsoft.com) to ensure high-quality, consistent comments. Focus on
writing **useful, clear documentation** that describes the member's **exposed behavior** and usage,
**avoiding internal implementation details** (unless an internal detail is necessary to clarify how to
use the API or what it returns).

## Focus on Exposed Behavior (Not Implementation)

- **Describe what the member does and how to use it**, rather than how it's implemented internally.
- Only include implementation details if they **affect inputs or outputs** in a way the caller needs to
  understand (e.g. performance implications, special conditions, side effects).
- **Preconditions and postconditions** are important: document any requirements (e.g. "parameter X
  cannot be null" or range limits) and effects (e.g. changes in state or global effects) that a caller
  should know.
- **Avoid simply restating the member name or signature**. Provide information that **adds value** for
  someone deciding whether to use this member.

## Key Documentation Elements and Their Content

When writing XML comments, include the following sections where appropriate:

- **`<summary>`** – *High-Level Summary*: Provide a concise overview of the member's purpose. This
  should help developers quickly decide **what the member does** and whether they need it.
  - *Example (method)*: "Calculates the total price after applying discounts."
  - *Example (property)*: "**Gets or sets the** maximum retry count for failed requests." (Use the
    standard phrasing for properties, e.g. **"Gets or sets the …"** for read-write properties, or just
    **"Gets the …"** if read-only, to match .NET conventions.)

- **`<remarks>`** – *Additional Details*: Include any information that doesn't fit in the summary but is
  important for using the member correctly. This may include:
  - Implementation details **relevant to the user** (e.g. algorithm notes or performance considerations)
    if it helps the user understand usage or side effects.
  - **Examples or scenarios** of usage, if it aids clarity (only include if it significantly improves
    understanding).
  - Any **background or context** that a developer should know (for example, mention thread safety, or
    how this member relates to others, etc.).

  Keep remarks informative but **avoid redundancy** with the summary.

- **`<param name="...">`** – *Parameter Descriptions*: For each method parameter, describe **what it
  represents and how it affects the method's behavior**. Focus on usage and expectations:
  - State what the parameter is **used for or influences**. For example: "`<param name="timeout">The
    maximum time, in seconds, to wait before the operation times out.</param>`" rather than just
    "timeout in seconds".
  - Mention any **valid ranges, units, or constraints** ("Must be positive"; "Cannot be null"; "If
    false, the method will..."). This helps callers know how to supply correct values.
  - If a parameter is complex (e.g. a callback or an options object), briefly explain **how it will be
    used** by the method.

- **`<returns>`** (for methods) – *Return Value Description*: Clearly describe **what the method
  returns**. This is not just the type, but the meaning of the return value and how a caller might use
  it. For example:
  - "`<returns>An array of strings containing the names of all active users. The array will be empty if
  no users are active.</returns>`"

  Explain any special return cases (e.g. "returns null if not found", or "returns 0 if the operation
  fails") so the developer knows what to expect.

- **`<value>`** (for properties) – *Property Value Description*: If documenting a property, use
  `<value>` to describe **the value held by the property**. For example:
  - "`<value>The current connection state of the database. True if connected; otherwise,
    false.</value>`"

  Use this tag to clarify what the property represents, especially if the property name is not
  self-explanatory.

- **`<exception>`** – *Exceptions*: Document exceptions that callers should be aware of **when best
  practice suggests doing so**. Include an `<exception>` tag for each exception type that the member
  **can throw in normal usage** (especially checked/expected exceptions or any usage-specific errors).
  For each:
  - Specify the **exception type** (e.g., `<exception cref="ArgumentNullException">`) and describe **the
    condition under which it is thrown** (e.g., "Thrown if <paramref name="filepath"/> is null or
    empty.").
  - It's generally not necessary to document common runtime exceptions (like `NullReferenceException`
    from internal code) unless the method is explicitly documented to throw them. Focus on exceptions
    that a caller might want to catch or prevent (invalid arguments, invalid operation states, etc.).
  - Example: `///<exception cref="InvalidOperationException">The connection is not open.</exception>`

- **`<example>`** (Optional) – *Usage Examples*: Include an example usage code block **only if it
  significantly clarifies how to use the member** or if the typical usage isn't obvious from
  summary/remarks.
  - If used, provide a short code snippet inside the `<example>` tag, along with a brief description if
    needed.
  - Ensure the example is **clear and focused** on the member's purpose. For simple or very common
    members, an example is usually unnecessary; for complex APIs, a well-chosen example can be very
    helpful.

*(Note: Omit any of the above tags if they are not applicable. For instance, a simple property might
need only `<summary>` and `<value>`.)*

## General Writing Guidelines

- **Conciseness vs. Usefulness**: Write in a clear, concise manner, but include enough detail to be
  useful. Avoid overly verbose descriptions that don't add value, but also avoid being so brief that
  important usage information is missing. Every sentence should help a developer understand the **what,
  why, or how** of the member. If a comment doesn't provide new information (e.g., just rephrases the
  member name), remove or refine it.

- **Audience-Appropriate Depth**: Tailor the documentation detail to the intended audience of the API:
  - For **common or beginner-friendly APIs**, use straightforward language and maybe a bit more
    explanation or context, assuming the developer might be less experienced. Define any domain-specific
    terms that a general developer might not know.
  - For **advanced or specialized APIs**, it's okay to assume more expertise. Focus on the specifics
    that an expert user needs, and use domain-specific terminology if the target audience will
    understand it. (Still, avoid unnecessary jargon and explain complexities clearly.)

- **Follow .NET Documentation Conventions**: Use the standard phrasing and style that official .NET
  documentation uses. Examples of conventions to follow:
  - **Properties**: Start summaries with **"Gets or sets…"** (or just "Gets…"/"Sets…" as appropriate) to
    describe the property. For example, *"Gets or sets the current log level for the logger."*
  - **Booleans**: For bool properties or return values, a common phrasing is *"**true** if ...;
    otherwise, **false**."*
  - Use **third-person descriptive voice** (e.g., "Returns the item…" instead of "Return the item…" or
    "This method returns…"). The tone should be professional and informative.
  - Write in **complete sentences**, and **end each sentence with a period**. XML comments are typically
    written as proper sentences (including in `<summary>`, `<remarks>`, etc.), and Visual Studio
    IntelliSense will display them as such.
  - Use the **present tense** for descriptions. For example, say "Calculates the value…" rather than
    "Will calculate the value…".
  - Use the form `<see langword="true"/>` rather than `<c>true</c>` where the comment contains a
    verbatim reference to a language keyword.

- **Structure and Order**: Organize the XML tags in the same logical order used in official docs and by
  convention: usually `<summary>` first, then `<remarks>` (if any), followed by `<param>` tags (one per
  parameter in the order of parameters), then `<returns>` (for methods) or `<value>` (for properties),
  then `<exception>` tags, and finally `<example>` (if included). This consistent ordering makes the
  documentation easy to read and scan, mirroring the structure seen on learn.microsoft.com and/or
  docs.microsoft.com examples.

- **Trim Unnecessary Details**: If the documentation becomes too lengthy or includes information that's
  not crucial for understanding the member's usage, **trim it down**. Developers typically read docs to
  decide how to use an API; focus on information that influences that decision or helps in using the API
  correctly. For example:
  - Omit internal algorithm details *unless* knowing them helps the user (e.g., mentioning that a method
    uses caching might explain why calling it repeatedly is cheap).
  - Avoid repeating information that can be inferred. (If a parameter name is `count` and the `<param>`
    description just says "The count.", that’s not helpful. Either expand on what "count" means in
    context or omit such a redundant comment.)
  - Ensure the **length is appropriate**: shorter for simple members, longer (but still focused) for
    complex ones. It's better to be slightly succinct than to overwhelm with extraneous info.

Only provide top-level documentation for the method 'Add' appearing in the context. The body of
the method 'Add' is provided for context information only; do not include it in the response.
Respond with a single XML documentation comment, and no other text.

This is the method 'Add' to analyze:

```

        ///
        public int Add(int a, int b)
        {
            return a + b;
        }

```
"
[PersistedCopilotSessionRepository Information] Persisted sessions are stored under C:\Users\klomb\source\repos\AntGame\.vs\AntGame\copilot-chat\52e570c1\sessions
[Conversations Information] Copilot auth status: OK. Copilot badge status: Active
[Conversations Error] [CopilotClient] Failed to talk to Copilot: Bad Request

[Conversations Warning] [CopilotClient] Issue with setting up the connection to 'https://api.githubcopilot.com/chat/completions', if you are using a proxy, check if HTTPS_PROXY is set correctly. https://learn.microsoft.com/en-us/dotnet/fundamentals/networking/http/httpclient#http-proxy
[Conversations Error] [Conversations] Unhandled exception in AskInConversationAsync: System.Exception: Error occurred while invoking intent 'None'.
Bad Request

   at Conversations.Kernel.ConversationBase.AskAsync(ConversationRequest requestContext, CancellationToken cancellation)
   at Conversations.Kernel.ConversationBase.AskAsync(ConversationRequest requestContext, CancellationToken cancellation)
   at Microsoft.VisualStudio.Conversations.Service.ServiceTarget.AskInConversationAsync(CopilotSessionId sessionId, CopilotRequest request, ActiveInteractions activeInteractions, IReadOnlyList`1 history, CopilotRequestOptions requestOptions, CancellationToken cancellation)
[CopilotSessionProvider Error] Unhandled exception invoking responder GitHub Copilot: StreamJsonRpc.RemoteInvocationException: Error occurred while invoking intent 'None'.
Bad Request

   at StreamJsonRpc.JsonRpc.<InvokeCoreAsync>d__156`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.VisualStudio.Copilot.ResponderBroker.<SendRequestHelperAsync>d__9.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.Copilot.ResponderBroker.<SendDirectRequestAsync>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore`1.GetResult(Int16 token)
   at Microsoft.VisualStudio.Copilot.Core.Agents.DefaultResponder.<RespondAsync>d__1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.VisualStudio.Copilot.Core.Agents.DefaultResponder.<RespondAsync>d__1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore`1.GetResult(Int16 token)
   at Microsoft.VisualStudio.Copilot.CopilotDefaultOrchestrator.<SendRequestToResponderAsync>d__22.MoveNext()
RPC server exception:
System.Exception: Error occurred while invoking intent 'None'.
Bad Request

      at Conversations.Kernel.ConversationBase.AskAsync(ConversationRequest requestContext, CancellationToken cancellation)
      at Conversations.Kernel.ConversationBase.AskAsync(ConversationRequest requestContext, CancellationToken cancellation)
      at Microsoft.VisualStudio.Conversations.Service.ServiceTarget.AskInConversationAsync(CopilotSessionId sessionId, CopilotRequest request, ActiveInteractions activeInteractions, IReadOnlyList`1 history, CopilotRequestOptions requestOptions, CancellationToken cancellation)
      at Microsoft.VisualStudio.Conversations.Service.CopilotServiceContainer.AskInConversationAsync(CopilotSessionId sessionId, CopilotRequest request, ActiveInteractions activeResponse, IReadOnlyList`1 history, CopilotRequestOptions requestOptions, CancellationToken cancellationToken)

[Yevrag35]

This just started happening today to all of my instances of VS 2022 Enterprise (17.14.11) as well. Only seems to be happening to the XML comment completion.

[anb2473]

Hi @KuroiLight,

From what you’ve described, this isn’t an issue with your C# code or XML documentation syntax — it’s a connectivity or request-handling problem between Visual Studio’s GitHub Copilot integration and the Copilot API. The “Bad Request” and proxy-related hints in your logs suggest that something in the environment is either interrupting the request or changing its format before it reaches GitHub’s servers. Since this only happens when trying to auto-generate XML summaries (///), it’s likely tied to the specific Copilot feature for comment completion rather than the general coding suggestions.

You’ve already tried resetting Visual Studio, repairing it, signing out and back in, and clearing cache files, which rules out many local configuration issues. The fact that another user reported the same behavior starting on the same day indicates that this might be a service-side change or regression in Copilot’s XML comment handling. In those cases, local fixes are often ineffective until the service or extension is updated.

That said, it’s still worth confirming there’s no proxy, firewall, or security software interfering with HTTPS traffic to https://api.githubcopilot.com. If you’re behind a proxy, check that the HTTPS_PROXY environment variable is set correctly for your system and that Visual Studio can use it. If no proxy is involved, you might try temporarily disabling strict network filtering or antivirus HTTPS inspection to see if it resolves the request failure.

If the issue persists after confirming network conditions, the next best step is to file a bug report through Visual Studio’s Help → Send Feedback → Report a Problem tool, referencing the error logs you’ve captured. This will give the Copilot and Visual Studio teams the context they need to reproduce and address the problem. In the meantime, you can still manually write XML documentation or use general Copilot suggestions by prompting it in an inline comment rather than relying on the /// shortcut.

Best of luck!

[KuroiLight]

Thanks for the information, I don't have any proxy settings set and the only thing I found that might be a problem is that I'm using NextDNS but after checking the logs it doesn't seem to be blocking anything related. The only other thing that I thought might be related was that it started right after installing some extensions, but I removed them right away after I noticed the issue and nothing changed so maybe it was coincidence. On the report a problem site, it won't let me submit the issue its giving me a 401 error when I try to send it.

[Yevrag35]

Also worth mentioning that this issue happens to both my desktop and work laptop that are in 2 different locations which have completely separate internet egresses. One is behind an enterprise network firewall and the other is at home on a residential network with absolutely no proxies or firewalls. And both starting displaying the exact same logs @KuroiLight posted to a T.

[Yevrag35]

I also tried to enter a problem/ticket and got 401 Unauthorized as well.

ERR_SEND_API: 401 Unauthorized: "You're not authorized." POST: /V2Verbatim authRequired=True **{"trackingId":"a069a41a4cec43d88196da749a769e04","source":"Send a smile","culture":"en-US","uiculture":"en-US","userType":"External","correlationIdentity":"28e31f9b-2170-46d5-ab0e-9d810f7c9f77:0:0","

[roncli]

I can confirm I'm getting this as well. I was able to add a ticket here: https://developercommunity.visualstudio.com/t/Error-creating-C-XML-Documentation-with/10949548

[FoleyRob]

I am also getting the same issue and am commenting here and also on your other ticket. Similar errors. Was working fine a couple weeks ago.

[roncli]

Microsoft confirmed that this was fixed. Huzzah! :)

[FoleyRob]

Well, this was fixed and then 17.14.13 was released and now it sometimes works and sometimes doesn't. I don't see the same exceptions in the copilot output window, it just doesn't seem to be reliably triggering the AI doc comments feature.