Uncaught exception: undefined when installing or starting plugins in Zotero 7

[NilsonPark]

Issue Description

After installing add-ons derived from this template in Zotero 7, the following error consistently appears in the Debug Output Console:

[JavaScript Error: "uncaught exception: undefined"]

This error occurs during the following actions:

• Installing the .xpi file
• Starting Zotero with the add-on installed
• Uninstalling the add-on

When the add-on is not installed, the error does not appear. This suggests that the issue originates from extensions built using this template.

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Test Environment

• Zotero version: 7.0.27 (64-bit)

• Operating System: Windows 11

• Add-ons tested:

  • Make It Red
  • Zotero Plugin Template
  • Zotero Better Notes

(All tested releases exhibit the same issue. Zotero’s official demo add-on “Make It Red” also triggers this error.)

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Steps to Reproduce

1. Open Zotero 7 (version 7.0.27, 64-bit).
2. Install any add-on derived from this template.
3. Go to Help → Debug Output Logging → Restart with Logging Enabled…
4. After restart, open Help → Debug Output Logging → View Output.
5. Observe the error message in the console.

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Sample Results

Zotero Plugin Template

Zotero Better Notes

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Additional Notes

I’ve observed this same “uncaught exception: undefined” message across multiple Zotero add-ons.

After some investigation, I traced the issue back to this plugin template, which suggests the root cause may lie in the shared structure or initialization code used across these add-ons.

This issue has been reproduced on Windows 11 and Ubuntu, and further testing on macOS is needed to verify whether it occurs consistently across platforms.

[northword]

As you said, Mark-It-Red also has a similar issue, so it's obvious that this issue is not caused by the structureor or initialization code of zotero-plugin-template.

[NilsonPark]

Good point. I find some other add-ons don’t exhibit this kind of error - for example, zotero-open-pdf. These add-ons are completely independent of this template.

Both Make It Red and zotero-plugin-template have this issue, while the others do not. I’m curious what causes this difference and how it can be fixed. Given the prevalence of this template, I believe the solution will help a lot, particularly for the developer community.

Additional Notes

Enabling or disabling an addon (startup or shutdown) will trigger this error while installing or uninstalling will not.

[northword]

Good example.

After comparing the structures, I found that zotero-open-pdf does not contain localization files. I removed the addon/locale directory in the Linter, and the error disappeared. Therefore, I believe this may be an error when Zotero loads plugin localization files.

[northword]

After a brief investigation, I confirmed that this error was thrown by this line of code.

https://github.com/zotero/zotero/blob/59a789c7508658b7c81a21d9ff9cfc05912ac1b5/chrome/content/zotero/xpcom/plugins.js#L487

reprod：

var { AddonManager } = ChromeUtils.importESModule("resource://gre/modules/AddonManager.sys.mjs"); 
var addon = (await AddonManager.getAllAddons())[0]
console.log("addon", addon)
var rootURI = addon.getResourceURI() 
console.log("rootURI", rootURI)
var sources = [new L10nFileSource(addon.id, "app", ["en-US"], rootURI.spec + 'locale/{locale}') ]
console.log("sources", sources)
L10nRegistry.getInstance().registerSources(sources);

[NilsonPark]

Thanks for the investigation. I think this issue is beyond the scope of this template or even Zotero.