diff --git a/chrome/content/zotero/xpcom/fileHandlers.js b/chrome/content/zotero/xpcom/fileHandlers.js
index a1fa4b1765..5a9bc2834b 100644
--- a/chrome/content/zotero/xpcom/fileHandlers.js
+++ b/chrome/content/zotero/xpcom/fileHandlers.js
@@ -171,9 +171,6 @@ Zotero.FileHandlers = {
 				catch (e) {
 					Zotero.logError(e);
 				}
-				finally {
-					Zotero.Utilities.Internal.Environment.restoreMozillaVariables();
-				}
 			}
 			
 			try {
@@ -522,9 +519,7 @@ Zotero.FileHandlers = {
 		Zotero.Utilities.Internal.Environment.clearMozillaVariables();
 		
 		// Do not await
-		var promise = Zotero.Utilities.Internal.exec(command, args);
-		
-		promise.finally(() => Zotero.Utilities.Internal.Environment.restoreMozillaVariables());
+		Zotero.Utilities.Internal.exec(command, args);
 	},
 };
 
diff --git a/chrome/content/zotero/xpcom/utilities_internal.js b/chrome/content/zotero/xpcom/utilities_internal.js
index abc44033e6..35545f588d 100644
--- a/chrome/content/zotero/xpcom/utilities_internal.js
+++ b/chrome/content/zotero/xpcom/utilities_internal.js
@@ -1929,6 +1929,7 @@ Zotero.Utilities.Internal = {
 		var startup = Services.startup;
 		if (restart) {
 			Zotero.restarting = true;
+			this.Environment.restoreMozillaVariables();
 		}
 		startup.quit(startup.eAttemptQuit | (restart ? startup.eRestart : 0));
 	},
@@ -3066,21 +3067,44 @@ Zotero.Utilities.Internal.Environment = {
 	 * using the wrong Firefox profile when launching URLs or PDFs. On Windows, it's not necessary
 	 * to call this when launching URLs, only processes.
 	 *
+	 * The variables are restored a (debounced) second after this is called. Restoring mostly isn't
+	 * necessary, since most new launches of Zotero would use the modified launcher, but a restart
+	 * on Linux (e.g., during an upgrade) skips our shell script where we set these variables.
+	 *
 	 * https://github.com/zotero/zotero/issues/4981
 	 */
 	clearMozillaVariables: function () {
+		const RESTORE_DEBOUNCE_DELAY = 1000;
+		
 		this.unset("MOZ_ALLOW_DOWNGRADE");
 		this.unset("MOZ_LEGACY_PROFILES");
+		
+		if (this._restoreTimeout) {
+			clearTimeout(this._restoreTimeout);
+			delete this._restoreTimeout;
+		}
+		
+		this._restoreTimeout = setTimeout(() => {
+			delete this._restoreTimeout;
+			this._restoreMozillaVariables();
+		}, RESTORE_DEBOUNCE_DELAY);
 	},
 	
 	/**
-	 * Re-set the Mozilla environment variables that we changed in the launcher
+	 * Immediately restore the Mozilla environment variables
 	 *
-	 * Call this in a finally() after using unsetMozillaVariables(). This mostly isn't necessary,
-	 * since most new launches of Zotero would use the modified launcher, but a restart on Linux
-	 * skips our shell script where we set these variables.
+	 * The variables are automatically restored shortly after they're cleared, but this can be
+	 * called before explicit restarts.
 	 */
 	restoreMozillaVariables: function () {
+		if (this._restoreTimeout) {
+			clearTimeout(this._restoreTimeout);
+			delete this._restoreTimeout;
+		}
+		this._restoreMozillaVariables();
+	},
+	
+	_restoreMozillaVariables: function () {
 		var env = Cc["@mozilla.org/process/environment;1"].getService(Ci.nsIEnvironment);
 		env.set("MOZ_ALLOW_DOWNGRADE", "1");
 		env.set("MOZ_LEGACY_PROFILES", "1");
diff --git a/chrome/content/zotero/xpcom/zotero.js b/chrome/content/zotero/xpcom/zotero.js
index 0e68211fa7..9776f8e33e 100644
--- a/chrome/content/zotero/xpcom/zotero.js
+++ b/chrome/content/zotero/xpcom/zotero.js
@@ -1032,9 +1032,6 @@ const { CommandLineOptions } = ChromeUtils.importESModule("chrome://zotero/conte
 				);
 			}
 		}
-		finally {
-			Zotero.Utilities.Internal.Environment.restoreMozillaVariables();
-		}
 	};
 	
 	
@@ -1062,9 +1059,7 @@ const { CommandLineOptions } = ChromeUtils.importESModule("chrome://zotero/conte
 		Zotero.Utilities.Internal.Environment.clearMozillaVariables();
 		
 		// Async, but we don't want to block
-		var promise = Zotero.Utilities.Internal.exec(applicationPath, args);
-		
-		promise.finally(() => Zotero.Utilities.Internal.Environment.restoreMozillaVariables());
+		Zotero.Utilities.Internal.exec(applicationPath, args);
 	};
 	
 	
@@ -1094,27 +1089,18 @@ const { CommandLineOptions } = ChromeUtils.importESModule("chrome://zotero/conte
 				if (!found.value) {
 					throw new Error(`Handler not found for '${scheme}' URLs`);
 				}
-				try {
-					if (!Zotero.isWin) {
-						Zotero.Utilities.Internal.Environment.clearMozillaVariables();
-					}
-					
-					svc.loadURI(Services.io.newURI(url, null, null));
-				}
-				finally {
-					if (!Zotero.isWin) {
-						Zotero.Utilities.Internal.Environment.restoreMozillaVariables();
-					}
+				if (!Zotero.isWin) {
+					Zotero.Utilities.Internal.Environment.clearMozillaVariables();
 				}
+				
+				svc.loadURI(Services.io.newURI(url, null, null));
 				return;
 			}
 		}
 		
-		var mozCleared = false;
 		try {
 			if (!Zotero.isWin) {
 				Zotero.Utilities.Internal.Environment.clearMozillaVariables();
-				mozCleared = true;
 			}
 			
 			var uri = Services.io.newURI(url, null, null);
@@ -1141,10 +1127,7 @@ const { CommandLineOptions } = ChromeUtils.importESModule("chrome://zotero/conte
 					+ "check extensions.zotero." + pref + " in about:config");
 			}
 			
-			if (!mozCleared) {
-				Zotero.Utilities.Internal.Environment.clearMozillaVariables();
-				mozCleared = true;
-			}
+			Zotero.Utilities.Internal.Environment.clearMozillaVariables();
 			
 			var proc = Components.classes["@mozilla.org/process/util;1"]
 							.createInstance(Components.interfaces.nsIProcess);
@@ -1153,11 +1136,6 @@ const { CommandLineOptions } = ChromeUtils.importESModule("chrome://zotero/conte
 			var args = [url];
 			proc.runw(false, args, args.length);
 		}
-		finally {
-			if (mozCleared) {
-				Zotero.Utilities.Internal.Environment.restoreMozillaVariables();
-			}
-		}
 	}