fix: pin App Insights WorkerService to 2.x (isolated-worker startup crash)#6
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…artup crash The deployed Function App crashed on startup (dotnet exit 134) with: System.TypeLoadException: Could not load type 'Microsoft.ApplicationInsights.Extensibility.ITelemetryInitializer' from assembly 'Microsoft.ApplicationInsights, Version=3.1.2...' so no functions loaded and the API returned 502 / no response. Microsoft.ApplicationInsights.WorkerService 3.1.2 pulls Microsoft.ApplicationInsights 3.x, whose type layout is incompatible with Microsoft.Azure.Functions.Worker.ApplicationInsights (2.x). Pinning WorkerService to 2.22.0 resolves Microsoft.ApplicationInsights back to the 2.x line (2.23.0), matching the Functions worker AI integration. Build stays 0 warnings / 0 errors with -warnaserror. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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…(prod recovery) (#23) INCIDENT 2026-06-22: Dependabot PR #22 bumped Microsoft.ApplicationInsights.WorkerService 2.22.0 -> 3.1.2 (reverting PR #6's pin); auto-merge + CD shipped it and the isolated worker crash-looped on startup (TypeLoadException: ITelemetryInitializer; host served 502). WorkerService 3.x pulls Microsoft.ApplicationInsights 3.x, incompatible with Worker.ApplicationInsights 2.x. Recovery: - Re-pin WorkerService to 2.22.0 (exact pin; resolves Microsoft.ApplicationInsights back to 2.23.0, the proven-good state). Build -c Release -warnaserror 0/0. Prevent recurrence (the comment alone wasn't a guard — Dependabot overrode it): - .github/dependabot.yml: ignore semver-major updates for Microsoft.ApplicationInsights.WorkerService AND Microsoft.ApplicationInsights. This ignore rule is the real enforcement. - Strengthened the csproj comment to reference PR #6, PR #22, this outage, and the ignore rule. Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Summary
Fixes a startup crash discovered during the first deploy of the Function App. The isolated worker exited with code 134 on boot:
No functions loaded; the deployed API returned 502 / no response on every route.
Root cause
Microsoft.ApplicationInsights.WorkerService3.1.2 pulls inMicrosoft.ApplicationInsights3.x, whose type layout is incompatible withMicrosoft.Azure.Functions.Worker.ApplicationInsights(2.51.0), which expectsITelemetryInitializerfrom the 2.x assembly. The mismatch throwsTypeLoadExceptionand crashes the host.Fix
Pin
Microsoft.ApplicationInsights.WorkerServiceto 2.22.0, which resolvesMicrosoft.ApplicationInsightsback to the 2.x line (2.23.0) — the version pairing the Functions worker App Insights integration. No application logic changed; onePackageReferenceversion + an explanatory comment.Validation
dotnet build -c Release -warnaserror→ 0 warnings / 0 errorsdotnet list package --include-transitive→Microsoft.ApplicationInsights 2.23.0(was 3.1.2)After merge, the app is redeployed and verified end-to-end (
GET /api/checks,GET /api/sla).🤖 Generated with Claude Code