Summary
After upgrading from v0.68.3 to v0.71.5 (and later testing v0.72.1), developer agents consistently fail when using the edit tool with OpenAI GPT models.
The same workflow works correctly with Claude Sonnet 4.6.
The failure appears related to malformed OpenAI tool-call serialization where tool_calls[].type becomes null.
Error
● Edit
│ Edit
│ back-end/app/src/main/java/eu/foobar/internal/services/RootService.java
└ Edit back-end/app/src/test/java/eu/foobar/internal/services/RootServiceI
Test.java
● Request failed (transient_bad_request). Retrying...
● Request failed (transient_bad_request). Retrying...
400 Invalid type for 'messages[43].tool_calls[1].type': expected one of 'function', 'all...ols', or 'custom', but got null instead.
Changes +2 -2
Duration 1m 8s
Tokens ↑ 571.3k • ↓ 5.6k • 482.2k (cached)
[copilot-harness] 2026-05-09T08:57:59.150Z attempt 1: process exit event exitCode=1
[copilot-harness] 2026-05-09T08:57:59.153Z attempt 1: process closed exitCode=1 duration=1m 9s stdout=11004B stderr=220B hasOutput=true
[copilot-harness] 2026-05-09T08:57:59.153Z attempt 1 failed: exitCode=1 isCAPIError400=false isMCPPolicyError=false isModelNotSupportedError=false isNullTypeToolCallError=true isAuthError=false hasOutput=true retriesRemaining=3
[copilot-harness] 2026-05-09T08:57:59.153Z attempt 1: null-type tool_call error (fresh run) — restarting fresh (poisoned history discarded; --continue disabled permanently)
[copilot-harness] 2026-05-09T08:57:59.153Z retry 1/3: sleeping 5000ms before next attempt (fresh run)
[copilot-harness] 2026-05-09T08:58:04.157Z retry 1/3: woke up, next delay cap will be 20000ms
[copilot-harness] 2026-05-09T08:58:04.157Z attempt 2: spawning: /usr/local/bin/copilot --add-dir /tmp/gh-aw/ --log-level all --log-dir /tmp/gh-aw/sandbox/agent/logs/ --disable-builtin-mcps --no-ask-user --allow-all-tools --allow-all-paths --add-dir /home/runner/work/foobar/foobar -p
[copilot-harness] 2026-05-09T08:58:04.160Z attempt 2: process started (pid=735)
Environment
gh-aw: v0.71.5 and v0.72.1
Previously working: v0.68.3
Engine: copilot-cli
Failing models: gpt-5.4
Working models: claude-sonnet-4.6
Run details - copilot 1.0.40
engine id: copilot
engine name: GitHub Copilot CLI
model: gpt-5.4
version: 1.0.40
agent version: 1.0.40
experimental: false
supports tools allowlist: true
run number: 80
run attempt: 1
ref: refs/heads/main
sha: f391c75574e141547c8edeef7bfd14e1e4aa5f74
event name: workflow_dispatch
staged: false
firewall enabled: true
awf version: v0.25.40
awmg version: (none)
steps: firewall: squid
created at: 2026-05-12T11:41:57.066Z
cli version: v0.71.5
Summary
After upgrading from v0.68.3 to v0.71.5 (and later testing v0.72.1), developer agents consistently fail when using the edit tool with OpenAI GPT models.
The same workflow works correctly with Claude Sonnet 4.6.
The failure appears related to malformed OpenAI tool-call serialization where tool_calls[].type becomes null.
Error
Environment
gh-aw: v0.71.5 and v0.72.1
Previously working: v0.68.3
Engine: copilot-cli
Failing models: gpt-5.4
Working models: claude-sonnet-4.6
Run details - copilot 1.0.40
engine id: copilot
engine name: GitHub Copilot CLI
model: gpt-5.4
version: 1.0.40
agent version: 1.0.40
experimental: false
supports tools allowlist: true
run number: 80
run attempt: 1
ref: refs/heads/main
sha: f391c75574e141547c8edeef7bfd14e1e4aa5f74
event name: workflow_dispatch
staged: false
firewall enabled: true
awf version: v0.25.40
awmg version: (none)
steps: firewall: squid
created at: 2026-05-12T11:41:57.066Z
cli version: v0.71.5