Why won't my theme editor load on the admin page?

Store Design

Topic summary

Users are experiencing issues with Shopify’s theme editor failing to load when clicking the customize button. The admin page loads normally, but the theme editor either loads extremely slowly or not at all.

Initial Troubleshooting Steps:

  • Clear browser cache and use supported browsers
  • Try Chrome Incognito mode or different devices
  • Reset internet connection
  • Test with other themes (like Debut) to isolate the issue

Identified Causes & Solutions:

  • Shopify outage: A brief platform-wide interruption occurred on June 18, 2021, which was quickly resolved
  • Third-party themes: Issues specific to certain themes (like Lorenza, WareHouse, Pipeline 2.0) may require contacting theme developers directly
  • Custom code conflicts: Removing custom blocks from schema without first deleting them in the customizer causes loading failures. Solution: restore the code, remove blocks via editor, then delete code
  • settings_data.json errors: Corrupted JSON files can prevent loading; editing and validating this file may resolve issues
  • Browser extensions/antivirus: Disabling browser extensions or antivirus software has resolved the problem for some users
  • Browser-specific: Some report it works in Microsoft Edge but not Chrome

Current Status:
The issue remains ongoing for multiple users across different years (2021-2023+), suggesting various root causes rather than a single platform-wide problem. Testing with default themes helps determine if the issue is theme-specific or system-wide.

Summarized with AI on November 2. AI used: claude-sonnet-4-5-20250929.
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Hi, @zacharytipton !

I appreciate these extra details.

Since this issue is only happening with the Lorenza theme, it’s possible that this problem may be tied to the theme specifically.

Lorenza is a third-party theme developed by Fluorescent Design Inc., so I recommend reaching out to them directly to confirm why this may be happening. You can contact these developers by viewing Lorenza in the Shopify Theme Store using this link, and then clicking ‘Support’ on the right hand side of the page.

Please keep me posted on how this goes!