T026

How do I stop our plugin from crashing the desktop after deploying a new version?

Ticket

Hi Twilio support, We're a small team running Flex 2.7.1 and we've been building out a custom plugin that we deploy through the Flex Plugins CLI. Things have been working pretty well overall, but we've run into a pattern we don't fully understand and wanted to ask if we're doing something wrong before assuming it's a problem on your end. Whenever we cut a new plugin version and push it out through a new Release, our agents on Chrome 124 start seeing a broken desktop — the UI loads but several panels are blank and they can't accept tasks. It clears up if we close and reopen the browser tab sometimes, but not reliably. We went ahead and rolled back to a prior configuration by releasing the older configuration SID and that fixed everyone immediately, so we know our new plugin version is involved somehow. Here's the part we're confused about: we've now reproduced this twice across two separate plugin versions that looked fine in our staging environment. Both times, the desktop breaks for all agents at once right after the release goes live. When we check the browser console there's a reference to something being undefined relating to a channel property, but we haven't been able to trace it back to a specific line in our plugin code. Our questions are basically: 1. Is there a recommended way to test a plugin version against a production-like environment before it affects all agents? 2. Is the Status Report tool the right place to start diagnosing what's happening during initialization, or is there something more specific we should be capturing? 3. Could the issue be that our plugin is running some initialization logic before certain Flex SDKs are fully ready, and if so, is there a safe event or lifecycle hook we should be waiting on? We're not in a rush but this is starting to slow down our deploys since we have to roll back every time. Happy to provide our account details or any other information if it helps. Thanks so much.

Gold label: bug / high

mistake... I see they say customer says they are not in a rush

Results by run

openai · gpt-5.5

2026-10-04 17:23 UTC · prompt ef0017a

config

medium

escalate: no

Summary

A newly released custom Flex plugin version is breaking the agent desktop for all users, but rolling back to the prior plugin configuration restores service.

Suggested first response

Thanks for the details. Since rolling back to the previous plugin configuration immediately resolves the issue, this most likely points to an error in the new custom plugin version rather than a Flex platform defect. Please capture a Flex Status Report from an affected session, along with the browser console stack trace, the active Release/Plugin Configuration SID, the previous known-good configuration SID, and the plugin version that introduced the issue. The Status Report is the right first diagnostic artifact, and we recommend checking the stack trace for 45601/custom plugin errors, recent Action overrides, component replacements, event listeners, and dependency changes. For safer testing, continue using a separate staging Flex environment where possible and only promote a tested plugin configuration to production; keeping the last known-good release available for immediate rollback is also recommended.

KB citations

kb-007

624 output tokens · 8.0s · 1 attempt(s)

anthropic · claude-sonnet-4-6

2026-10-04 17:20 UTC · prompt ef0017a

how_to

medium

escalate: no

Summary

Customer's custom Flex plugin consistently breaks the agent desktop for all agents after each new release, with a workaround of rolling back to the prior configuration SID, and they are asking for best practices on safe deployment, diagnostics, and plugin initialization lifecycle.

Suggested first response

Thank you for the detailed write-up — this is really helpful context. Based on what you've described, the pattern (all agents affected simultaneously right after a release, immediate recovery on rollback to the prior configuration SID) is consistent with the new plugin version introducing a runtime error during initialization, likely before one or more Flex SDKs are fully ready. A few targeted suggestions: 1. **Canary / staged releases**: The Flex Plugins CLI supports releasing a plugin version to a subset of agents by creating a Plugin Configuration that includes the new version and activating it as a Flex Release only for a test group. This lets you validate against production data and infrastructure without exposing all agents. 2. **Diagnostics — Status Report and browser console**: Yes, the Status Report (available since Flex UI 1.32) is the right starting point. Ask a affected agent to export it immediately after the breakage occurs; it contains structured logs and error details far more useful than a screenshot. Pair that with the browser Console and Network tabs in Developer Tools. The 'undefined' channel property reference you're seeing in the console is the key signal — capturing the full stack trace from the console at the moment of breakage will help pinpoint whether it's a 45600 (Flex UI platform) or 45601 (custom plugin) error. 3. **Initialization lifecycle**: This is a very common root cause for the pattern you're describing. Plugins should not access Flex SDK objects (TaskRouter Worker, Conversations, Voice, Sync) until the relevant manager or service is confirmed ready. The recommended pattern is to gate initialization logic on Flex lifecycle events such as `Flex.Manager` being fully initialized and listening for SDK-specific ready events rather than running logic synchronously at plugin registration time. Review any Action overrides (especially around task acceptance) and event listeners added in your plugin's `init` method for code that assumes SDK state is available immediately. If after capturing the Status Report and full console stack trace you cannot identify the offending line, please share your account SID and the specific error text and we can dig deeper with you.

KB citations

kb-007

560 output tokens · 17.1s · 1 attempt(s)