[GH-ISSUE #5242] [Bug] Dashboard 'Clear Offline' button fails with 'Unexpected end of JSON input' #4068

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opened 2026-05-05 14:34:35 -06:00 by gitea-mirror · 1 comment

gitea-mirror commented

2026-05-05 14:34:35 -06:00

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Originally created by @mango766 on GitHub (Mar 17, 2026).
Original GitHub issue: https://github.com/fatedier/frp/issues/5242

Bug Description

Clicking the Clear Offline button on the frps dashboard fails with the error:

Failed to clear offline proxies: Failed to execute 'json' on 'Response': Unexpected end of JSON input

This is caused by two related issues:

Backend (pkg/util/http/handler.go): When an API handler returns nil, MakeHTTPHandlerFunc responds with HTTP 200 and an empty body. Per REST conventions, an empty-body response should use 204 No Content instead.
Frontend (web/frps/src/api/http.ts): The request() function unconditionally calls response.json() on any non-204 response. When the response body is empty or lacks a Content-Type: application/json header, the browser throws Unexpected end of JSON input.

Notably, the frpc dashboard's http.ts already checks Content-Type before parsing JSON — the frps dashboard version was missing this same check.

Steps to Reproduce

Start frps with the dashboard enabled
Connect one or more frpc clients, then disconnect them so proxies go offline
Open the frps dashboard, go to the Proxies page
Click Clear Offline → observe the error popup

Expected Behavior

Offline proxies should be cleared successfully with a success toast notification.

Environment

frp version: 0.67.0
OS: Linux/Windows (reproducible on both)

This was independently reported by at least two users:

#5233
#5236

Originally created by @mango766 on GitHub (Mar 17, 2026). Original GitHub issue: https://github.com/fatedier/frp/issues/5242 ### Bug Description Clicking the **Clear Offline** button on the frps dashboard fails with the error: > Failed to clear offline proxies: Failed to execute 'json' on 'Response': Unexpected end of JSON input This is caused by two related issues: 1. **Backend (`pkg/util/http/handler.go`)**: When an API handler returns `nil`, `MakeHTTPHandlerFunc` responds with HTTP 200 and an empty body. Per REST conventions, an empty-body response should use 204 No Content instead. 2. **Frontend (`web/frps/src/api/http.ts`)**: The `request()` function unconditionally calls `response.json()` on any non-204 response. When the response body is empty or lacks a `Content-Type: application/json` header, the browser throws `Unexpected end of JSON input`. Notably, the frpc dashboard's `http.ts` already checks `Content-Type` before parsing JSON — the frps dashboard version was missing this same check. ### Steps to Reproduce 1. Start `frps` with the dashboard enabled 2. Connect one or more `frpc` clients, then disconnect them so proxies go offline 3. Open the frps dashboard, go to the Proxies page 4. Click **Clear Offline** → observe the error popup ### Expected Behavior Offline proxies should be cleared successfully with a success toast notification. ### Environment - frp version: 0.67.0 - OS: Linux/Windows (reproducible on both) ### Related This was independently reported by at least two users: - #5233 - #5236