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Use this article when clicking Start Session produces nothing, returns an internal error, or the Pear Deck for Google Slides Add-on fails to load before class begins. Work through each section in order. Most launch issues resolve at the extension or browser step.

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Check Your Extension

The Pear Deck for Google Slides Add-on must be installed and enabled before you can start a session from Google Slides.
  1. Open Google Slides and go to Extensions in the top menu.
  2. Confirm that Pear Deck for Google Slides Add-on appears in the list.
  3. Select Pear Deck for Google Slides Add-on → Open Pear Deck Add-on to open the sidebar.
If the Add-on does not appear in the Extensions menu, it is not installed. See Fix the Pear Deck Add-on Not Loading in Google Slides for installation and permission steps.
If the Add-on appears in the menu but the sidebar loads blank or immediately closes, skip to Verify Your Browser and Cookie Settings below.
Confirm the Add-on is up to date:
  1. In Chrome, go to chrome://extensions.
  2. Turn on Developer mode in the top-right corner.
  3. Click Update to force an update check for all installed extensions.
  4. Reload Google Slides and try starting the session again.
You can also start a Pear Deck session without the Google Slides Add-on by going directly to app.peardeck.com/home and presenting from your lesson library. If you need the session to start immediately, this is the fastest path.
Pear Deck requires cookies from several domains to authenticate your account and maintain a live session. If those cookies are blocked, the Add-on sidebar will fail to load or the Start Session button will not respond. Confirm cookies are allowed:
  1. In Chrome, go to Settings → Privacy and security → Third-party cookies.
  2. Under Allowed to use third-party cookies, confirm the following domains are present. Add any that are missing.
    • *.peardeck.com
    • *.google.com
    • *.youtube.com
    • sign-in.microsoftonline.com
  3. Reload Google Slides and try starting the session again.
For full browser-specific cookie instructions, see Allow Cookies for Pear Deck.
Safari is not supported for teacher-facing Pear Deck features, including session launch. Use the latest version of Chrome, Firefox, or Edge. Students can join sessions on Safari.
Clear the cache if cookies are already allowed:
  1. In Chrome, go to Settings → Privacy and security → Clear browsing data.
  2. Select Cached images and files and click Clear data.
  3. Close all Google Slides tabs, then reopen your presentation and try again.

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Confirm Your Sign-In

To launch a session, you must be signed in to Pear Deck with the correct account. A mismatch between your Google account in Chrome and your Pear Deck account is a common cause of errors.
  1. Go to app.peardeck.com/home and confirm you are signed in.
  2. Verify that the account shown matches the Google or Microsoft account you use at school. If you have a personal Pear Deck account and a school account, make sure you are using the school account.
  3. If your school uses Google SSO or Microsoft SSO, sign out of Pear Deck and sign back in through your school’s identity provider.
  4. Return to Google Slides and try starting the session again.
If you see “Sign in to continue” inside the Add-on sidebar even though you believe you are signed in, the Add-on session has expired. Select Sign in inside the sidebar and complete the sign-in flow without closing the sidebar.

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Review Your Network Settings

Pear Deck uses several external domains to serve content, handle real-time responses, and maintain the session connection. If your school’s network or firewall blocks any of these, the session will fail to start or will drop mid-class. Required domains to allow: Run the network diagnostic:
  1. Open app.peardeck.com/networktest on the affected device.
  2. Review the results. Any blocked item identifies a domain that needs to be added to the network allowlist.
  3. Share the results with your IT admin if you cannot update firewall settings yourself.
For the complete list of required domains and client IDs, see Technical Requirements for Pear Deck.

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Confirm Which Mode Your Session Is Using

Pear Deck sessions launch differently depending on the mode. If you are not sure which mode applies to your lesson, the difference may explain why the session is not behaving as expected. Teacher-paced sessions:
  • You control which slide students see. Students cannot advance on their own.
  • Requires the Pear Deck for Google Slides Add-on or Pear Deck Home to be open and active.
  • The session closes when you end it or close the presenter view.
Student-paced sessions:
  • Students navigate through slides independently. You do not need to keep the session open.
  • Does not require the Add-on to be running after you start the session.
  • Start a student-paced session from the Sessions page: locate the session, select More Actions, and choose Turn on Student-Paced.
If you intended to start a student-paced session but the Add-on sidebar is preventing launch, go directly to app.peardeck.com/home/sessions and switch the session to student-paced from there.
To switch from teacher-paced to student-paced, the session must be in Live status. If it is Closed, reopen it first, then switch to student-paced.

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Collect This Before Contacting Support

If you have worked through all sections above and the session is now running, no further action is needed. If it still will not start, contact GoGuardian Support. Gathering the following information before reaching out reduces the time it takes to diagnose the issue.
  • Browser name and version: In Chrome, go to Help → About Google Chrome to see the version number.
  • Extension version: In Chrome, go to chrome://extensions, find Pear Deck for Google Slides Add-on, and note the version number shown under the extension name.
  • Error message: Copy the full text of any error message displayed in the Add-on sidebar or on the Pear Deck page. A screenshot of the error is also helpful.
  • Network type: Note whether you are on the school network, a home network, or a mobile hotspot. If on the school network, confirm whether a VPN is active.
  • Steps already tried: List the sections from this article you completed and what you observed after each step.
Contact GoGuardian Support.
Last modified on July 16, 2026