diff --git a/app/scripts/fetch_xulrunner b/app/scripts/fetch_xulrunner
index b90c0003d9..2b57bfbc22 100755
--- a/app/scripts/fetch_xulrunner
+++ b/app/scripts/fetch_xulrunner
@@ -209,8 +209,10 @@ function modify_omni {
 	# Accept zotero@chnm.gmu.edu for target application to allow Zotero 6 plugins to remain
 	# installed in Zotero 7
 	replace_line "if \(targetApp.id == Services.appinfo.ID\) \{" "if (targetApp.id == 'zotero\@chnm.gmu.edu') targetApp.id = '$APP_ID'; if (targetApp.id == Services.appinfo.ID) {" modules/addons/XPIDatabase.jsm
-	# Fix addon.id is undefined with built-in theme addons, anyway we don't support theme addons
-	replace_line 'addon.type === "theme"' 'false' modules/addons/XPIDatabase.jsm
+	
+	# TEMP: Skip addons without ids until we figure out what's going on with the default theme.
+	# This fixes plugin updating and other things.
+	replace_line 'return addons;' 'return addons.filter(addon => addon.id);' modules/addons/XPIDatabase.jsm
 	
 	# For updates, look for applications.zotero instead of applications.gecko in manifest.json and
 	# use the app id and version for strict_min_version/strict_max_version comparisons