Reported issues for Tidewave Phoenix

Pod holds 23 of 88 problems reported by people outside the maintainer team. Issues filed by the project's own owners, members and collaborators are excluded entirely — a maintainer's release checklist is not a warning to a prospective user.

Back to Tidewave Phoenix.

Most discussed

ACP preload fails (ZodError / “Cannot preload without client”)

What is your operating system?

macOS (darwin/arm64)

What is your Elixir version?

Elixir 1.18.4 (compiled with Erlang/OTP 27)

What is your Phoenix version?

1.8.3

What is your Tidewave version?

0.5.4

Current behavior

I’m using Tidewave Web with Phoenix following the current documentation (Phoenix Plug + Tidewave CLI + *.localhost secure context).

The UI connects to MCP successfully, but any attempt to start a chat or perform actions fails during ACP preload. The bro

Read the thread · 2026-01-27 · closed · external user · 9 comments

Unable to configure Github Copilot provider

What is your operating system?

MacOS

What is your Elixir version?

1.18

What is your Phoenix version?

1.8.0

What is your Tidewave version?

0.4

Current behavior

When I try to configure the github copilot provider it takes me to github and everything looks to be working. Integration set up... all good, but then it just stays on github page, doesn't take me back to localhost:4000/tidewave. When I manually go back to localhost with tidewave, the configuration did not stic

Read the thread · 2025-09-07 · closed · external user · 9 comments

claude code can't authorize

Which editor/MCP client are you using?

claude code

Are you using a MCP proxy?

Is your web application working correctly?

yes

What is your operating system?

arch

What is your Tidewave version?

~> 0.4

Current behavior

tidewave is working in my browser and i have a few messages with it so far.

claude code can't do much other than detect the MCP.

╭──────────────────────────────────────────────────────────────────────────────────────────────────────────────

[Read the thread](https://github.com/tidewave-ai/tidewave_phoenix/issues/173) · 2025-09-02 · closed · external user · 17 comments

### Can't register Tidewave in Claude Code (requests end up in application router)

### Which editor/MCP client are you using?

Claude Code 1.0.55 (via the bun-based installer, see below)

### Are you using a MCP proxy?

No

### Is your web application working correctly?

```bash
$ curl -v http://localhost:4011/tidewave/mcp

*   Trying 127.0.0.1:4011...
* Connected to localhost (127.0.0.1) port 4011 (#0)
> GET /tidewave/mcp HTTP/1.1
> Host: localhost:4011
> User-Agent: curl/7.88.1
> Accept: */*
>
< HTTP/1.1 200 OK
< cache-control: no-cache
< connection: keep-alive
< content-typ

[Read the thread](https://github.com/tidewave-ai/tidewave_phoenix/issues/128) · 2025-07-18 · closed · external user · 12 comments

### Unknown registry: Tidewave.MCP.Registry

### Which editor/MCP client are you using?

Claude Code

### Are you using a MCP proxy?

No

### Is your web application working correctly?

* Host localhost:4000 was resolved. * IPv6: ::1 * IPv4: 127.0.0.1 *   Trying [::1]:4000... * connect to ::1 port 4000 from ::1 port 60158 failed: Connection refused *   Trying 127.0.0.1:4000... * Connected to localhost (127.0.0.1) port 4000 * using HTTP/1.x > GET /tidewave/mcp HTTP/1.1 > Host: localhost:4000 > User-Agent: curl/8.13.0 > Accept: */* > * Reque

[Read the thread](https://github.com/tidewave-ai/tidewave_phoenix/issues/101) · 2025-06-18 · closed · external user · 12 comments

### Route not found

### Which editor/MCP client are you using?

Zed

### Are you using a MCP proxy?

yes

### Is your web application working correctly?

no

### What is your operating system?

OSX

### What is your Tidewave version?

0.1

### Current behavior

When activating the MCP server I'm getting this in the Phoenix logs:

[info] POST /tidewave/mcp [debug] ** (Phoenix.Router.NoRouteError) no route found for POST /tidewave/mcp (TtestWeb.Router) (ttest 0.1.0) deps/phoenix/lib/phoenix/router.ex:541: Ttes

Read the thread · 2025-05-25 · closed · external user · 10 comments

Windows/Claude Desktop

Hello,

Trying to run Tidewave on Windows with Claude desktop and Elixir mcp proxy , keep getting the errors in the attached file and the below on the command line :

19:30:54.329 [error] Failed to parse SSE event!

19:30:54.336 [info] SSE connection closed. Trying to reconnect in 1s.

mcp-server-tidewave.log

Read the thread · 2025-05-01 · closed · external user · 21 comments

Bug: SSE error when using Cursor

Using Cursor's latest (I'm on the nightly branch)

Installed Tidewave, set up MCP as described in the Tidewave docs

Getting the following SSE error - screenshots below:

To recreate:

Start Phoenix with Tidewave installed
Navigate to https://localhost:4000/tidewave/mcp
Navigate to the data endpoint URL displayed (http://localhost:4000/tidewave/mcp/message?sessionId=8e6a5e81-833d62f4-3305d87c)

If I cycle the MCP server (toggle on/off) the error disappears

Error:

[error] ** 

[Read the thread](https://github.com/tidewave-ai/tidewave_phoenix/issues/19) · 2025-04-29 · closed · external user · 11 comments

## Most recent

### Support opt-in staging releases without Mix and server-side tool selection

## Use case

We use Tidewave in an authenticated internal staging environment where non-developer teammates use Claude Code and Vision mode to record UI tutorials.

The desired environment split is:

- `dev`: full Tidewave tool set
- `staging`: a limited server-side tool set, such as browser tools only
- `prod`: no Tidewave dependency or plug

A consumer can already scope the dependency with `only: [:dev, :staging]`. However, `Tidewave.Application` currently starts the MCP supervisor only when t

[Read the thread](https://github.com/tidewave-ai/tidewave_phoenix/issues/275) · 2026-08-28 · open · external user · 1 comment

### project_eval never reloads code in non-Phoenix projects (v0.9.0)

`Tidewave.MCP.Tools.Eval.eval_code/5` reloads before every evaluation, but only when a Phoenix endpoint is present:

```elixir
# lib/tidewave/mcp/tools/eval.ex
if endpoint = assigns[:phoenix_endpoint] do
  Phoenix.CodeReloader.reload(endpoint)
end

Tidewave.call/2 sets phoenix_endpoint: conn.private[:phoenix_endpoint], which is nil for the non-Phoenix setup the README documents under "In non-Phoenix applications" (bandit + a mix tidewave alias). So that branch never runs, and the nod

Read the thread · 2026-08-23 · closed · external user · 1 comment

Plug.Conn.register_before_send/2 crashes on diagnostic GET with Plug 1.20

Which editor/MCP client are you using?

Codex, using MCP.

Are you using a MCP proxy?

Is your web application working correctly?

The MCP endpoint is reachable. A GET request returns: HTTP/1.1 405 Method Not Allowed Method Not Allowed Command: curl -v http://localhost:4000/tidewave/mcp

What is your operating system?

Linux, Fedora Silverblue.

What is your Tidewave version?

0.8.3.

Current behavior

With Tidewave 0.8.3 and Plug 1.20.3, a same-origin

Read the thread · 2026-08-14 · closed · external user · 1 comment

Tidewave Web: with local_port discovery the client rewrites the MCP target to localhost keeping the https scheme, breaking TLS-terminating dev proxies

What is your operating system?

macOS (Apple Silicon)

What is your Elixir version?

1.15.7 (Erlang/OTP 26)

What is your Phoenix version?

1.7.10

What is your Tidewave version?

0.6.1 (hex package) / 0.4.5 (CLI)

Current behavior

Setup: Phoenix dev server on plain HTTP (localhost:4000), with a local TLS-terminating reverse proxy (Caddy) in front of it:

https://app.example.com → localhost:4000 (Phoenix)
https://tidewave.example.com → Tidewave CLI (`tidewave --a

Read the thread · 2026-07-01 · closed · external user · 2 comments

before_send callback crashes with AlreadySentError on WebSocket upgrades

Description

When plug Tidewave is enabled and a request is upgraded to a WebSocket (via WebSockAdapter.upgrade/4 / Plug.Conn.upgrade_adapter/3), the before_send callback registered in Tidewave.call/2 crashes with Plug.Conn.AlreadySentError.

Root cause

In call/2, Tidewave registers a before_send that mutates response headers:

def call(conn, _opts) do
  conn
  |> validate!()
  |> Plug.Conn.register_before_send(fn conn ->
    conn
    |> maybe_rewrite_csp()
    |

[Read the thread](https://github.com/tidewave-ai/tidewave_phoenix/issues/247) · 2026-06-30 · closed · external user · 2 comments

### (RuntimeError) get_sock_data not supported by Plug.Cowboy.Conn

### Which editor/MCP client are you using?

Tidewave web

### Are you using a MCP proxy?

No

### Is your web application working correctly?

* Host localhost:55110 was resolved. * IPv6: ::1 * IPv4: 127.0.0.1 *   Trying [::1]:55110... * connect to ::1 port 55110 from ::1 port 52189 failed: Connection refused *   Trying 127.0.0.1:55110... * Connected to localhost (127.0.0.1) port 55110 > GET /tidewave/mcp HTTP/1.1 > Host: localhost:55110 > User-Agent: curl/8.7.1 > Accept: */* > * Request complete

[Read the thread](https://github.com/tidewave-ai/tidewave_phoenix/issues/246) · 2026-06-25 · closed · external user · 2 comments

### Support system HTTP/HTTPS proxy environment variables

### Which editor/MCP client are you using?

vscode

### Are you using a MCP proxy?

_No response_

### Is your web application working correctly?

_No response_

### What is your operating system?

windows

### What is your Tidewave version?

0.5

### Current behavior

Tidewave currently does not appear to use the system-configured proxy settings or standard proxy environment variables such as:

- HTTP_PROXY
- HTTPS_PROXY
- http_proxy
- https_proxy

This can cause connection issues in environmen

[Read the thread](https://github.com/tidewave-ai/tidewave_phoenix/issues/243) · 2026-05-18 · closed · external user · 3 comments

### Unable to use MCP in Claude Code due to auth issue

### Which editor/MCP client are you using?

Claude Code

### Are you using a MCP proxy?

No

### Is your web application working correctly?

➜ moonshot_engine git:(db/qa_testing) ✗ curl -v http://localhost:4000/tidewave/mcp

Host localhost:4000 was resolved.
IPv6: ::1
IPv4: 127.0.0.1
Trying [::1]:4000...
connect to ::1 port 4000 from ::1 port 61819 failed: Connection refused
Trying 127.0.0.1:4000...
Connected to localhost (127.0.0.1) port 4000

GET /tidewave/mcp HTTP/1.1

Read the thread · 2026-05-01 · closed · external user · 6 comments

notifications/roots/list_changed crashes handle_message/2 with FunctionClauseError

Which editor/MCP client are you using?

Claude Code

Are you using a MCP proxy?

no proxy

Is your web application working correctly?

Yes, the app is working correctly. Tidewave responds, MCP tools work over POST as expected.

What is your operating system?

macOS 26.4.1

What is your Tidewave version?

0.5.6

Current behavior

When Claude Code is connected to the Tidewave MCP endpoint, it sends the standard MCP notification notifications/roots/list_changed to inform t

Read the thread · 2026-05-01 · closed · external user · 3 comments

Failed connection to Github - 403

What is your operating system?

Ubuntu

What is your Elixir version?

1.19

What is your Phoenix version?

1.17

What is your Tidewave version?

latest

Current behavior

I have used Tidewave many times before and starting a new project, went to connect back to Github and it shows successful via Github however getting the 403 error on your end. I tried 4 times and still nothing.

<img width="1236" height="365" alt="Image" src="https://github.com/user-attachments/assets/b72c

Read the thread · 2026-03-04 · closed · external user · 2 comments

Tidewave Web performance degradation when Tidewave browser tab is active/focused

What is your operating system?

Ubuntu 24.04

What is your Elixir version?

1.18.1, Erlang/OTP: 27.3.3 (erts 15.2.6)

What is your Phoenix version?

1.7.21

What is your Tidewave version?

0.5.4

Current behavior

First of all, thanks for the awesome tool! 👍

While working on optimizing the performance of an application's business logic, I noticed a difference in performance that, after clarification, turned out to be quite significant for the task I was working on.

**Enviro

Read the thread · 2026-02-23 · open · external user · 4 comments

get_docs for test-only dependencies

What is your operating system?

macOS

What is your Elixir version?

1.19.5

What is your Phoenix version?

1.8.3

What is your Tidewave version?

0.5.5

Current behavior

The get_docs tool cannot retrieve function documentation for test-only dependencies like phoenix_test.

I'm running the phoenix server in dev env (like I assume most people do).

Expected behavior

Allow access to function docs of test-only dependencies via get_docs, so that I can use Tidewave w

Read the thread · 2026-02-17 · closed · external user · 3 comments

Livebook + Tidewave

Which editor/MCP client are you using?

default tidewave mcp

Are you using a MCP proxy?

Is your web application working correctly?

Yes

What is your operating system?

OSX

What is your Tidewave version?

0.5

Current behavior

While running livebook and tidewave I keep getting this:

  ⎿  Error: Failed to evaluate code. Process exited with reason: exited in: GenServer.call(:standard_error, {:add_target, #PID<0.8440.0

[Read the thread](https://github.com/tidewave-ai/tidewave_phoenix/issues/222) · 2026-02-01 · closed · external user · 2 comments

### Failed to download agent ACP executable: Download failed

### What is your operating system?

Windows (host) / Debian (WSL)

### What is your Elixir version?

Elixir 1.18.4

### What is your Phoenix version?

1.8.1

### What is your Tidewave version?

0.5.4

### Current behavior

I tried Tidewave OSS in the past with just Copilot, and everything used to work just fine - pretty straightforward. Now that the company I work for is paying for Tidewave, I'm trying to test different setups. However,r it doesn't seem to be possible to connect to Codex for som

[Read the thread](https://github.com/tidewave-ai/tidewave_phoenix/issues/220) · 2026-01-25 · closed · external user · 3 comments

### /proxy endpoint returns 403 for browser requests with Origin header despite allow_remote_access = true

### What is your operating system?

Mac OS 15.7.3

### What is your Elixir version?

1.18.4 (Erlang/OTP 27)

### What is your Phoenix version?

1.8.3

### What is your Tidewave version?

0.5.4 (hex package) / 0.3.0 (macOS app)

### Current behavior

When accessing Tidewave Web from a remote browser on the local network, it gets stuck on "Connecting to your app" with the error:

  [Error] Failed to establish MCP connection using streamable HTTP transport.
  Error: Error POSTing to endpoint (HTTP 

[Read the thread](https://github.com/tidewave-ai/tidewave_phoenix/issues/219) · 2026-01-24 · closed · external user · 5 comments

The remaining reports are on [the project's issue tracker](https://github.com/tidewave-ai/tidewave_phoenix/issues).