Antigravity IDE 2.0.3 fails after login with "Failed to fetch" and agent server connection errors on Intel macOS

[Shrikant_Govande]

I am unable to complete Antigravity IDE setup after successful Google authentication.

The IDE launches correctly, login succeeds, and the language server starts, but the Antigravity agent functionality never becomes available.

The UI displays:

Error: [unknown] Failed to fetch

and later shows:

antigravity client: couldn't create connection to server

Environment

Antigravity IDE Version: 2.0.3
VSCode OSS Version: 1.107.0
Commit: 4e2e10a9285aefbdcb898ae5e50dde45e9c7f505
Date: 2026-05-22T00:37:08.848Z
Electron: 39.2.3
Chromium: 142.0.7444.175
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Darwin x64 21.6.0 (Intel Mac)
Language Server CL: 919335958

What Works

• Antigravity IDE launches successfully.

• Google authentication completes successfully.

• OAuth redirect succeeds.

• Language server process starts successfully.

• Application is notarized and accepted by macOS.

What Fails

The onboarding/setup flow fails with:

Error: [unknown] Failed to fetch

The IDE notification shows:

antigravity client: couldn't create connection to server

In Developer Tools Network tab, the following requests repeatedly fail:

GetAgentScripts
GetMcpServerStates
RefreshMcpServers
GetAgentFlags
ListPages

Diagnostics

The Antigravity language server is running:

language_server_macos_x64

A local service is listening on a dynamic localhost port:

TCP localhost:54162 (LISTEN)

However the IDE cannot successfully communicate with the agent services and all agent-related requests fail.

macOS verification:

spctl --assess --verbose "/Applications/Antigravity IDE.app"

Result:
accepted
source=Notarized Developer ID

Troubleshooting Already Attempted

• Restarted Antigravity IDE

• Reauthenticated with Google account

• Verified language server startup

• Verified application notarization

• Reinstalled Antigravity IDE

• Checked local listening ports

• Inspected Developer Tools Network requests

Question

Is this a known issue with Antigravity IDE 2.0.3 on Intel macOS (Darwin x64 21.6.0)?

If additional logs are needed, I can provide screenshots, process information, network traces, and console output.

[xplicit-dev]

@Shrikant_Govande
I got the same issue while using Antigravity IDE v2.0.4.

The issue was resolved by correcting the localhost entries in /etc/hosts.

I added the following mappings:

127.0.0.1 localhost
::1 localhost

After updating /etc/hosts and restarting Antigravity IDE, the onboarding process completed successfully and the agent functionality became available.

During troubleshooting, I found that the language_server_macos_x64 process was starting successfully and listening on a dynamic local port:

lsof -iTCP:<port> -sTCP:LISTEN -P -n

Output:

language_server_macos_x64
TCP [::1]:<port> (LISTEN)

The service was reachable using:

curl -vk https://localhost:<port>
curl -g -vk https://[::1]:<port>

However, Antigravity was reporting:

ConnectError: [unavailable] connect ECONNREFUSED 127.0.0.1:<port>

which indicated that the client was unable to connect to the local service.