diff --git a/chrome/content/zotero/xpcom/schema.js b/chrome/content/zotero/xpcom/schema.js
index f8dd3df05d..0ad232ca6e 100644
--- a/chrome/content/zotero/xpcom/schema.js
+++ b/chrome/content/zotero/xpcom/schema.js
@@ -53,6 +53,7 @@ Zotero.Schema = new function(){
 	var _nextRepositoryUpdate;
 	var _remoteUpdateInProgress = false;
 	var _localUpdateInProgress = false;
+	var _hiddenNoticesWithoutIDs = new Map();
 	
 	var self = this;
 	
@@ -2364,6 +2365,8 @@ Zotero.Schema = new function(){
 		var translatorUpdates = xmlhttp.responseXML.getElementsByTagName('translator');
 		var styleUpdates = xmlhttp.responseXML.getElementsByTagName('style');
 		
+		_showRepositoryMessage(xmlhttp.responseXML);
+		
 		if (!translatorUpdates.length && !styleUpdates.length){
 			await Zotero.DB.executeTransaction(function* (conn) {
 				// Store the timestamp provided by the server
@@ -2415,6 +2418,111 @@ Zotero.Schema = new function(){
 	}
 	
 	
+	/**
+	 * Show dialog if repo returns a message
+	 */
+	function _showRepositoryMessage(responseXML) {
+		try {
+			var messageElem = responseXML.querySelector('message');
+			if (!messageElem || !messageElem.textContent) {
+				return;
+			}
+			
+			let hiddenNotices = Zotero.Prefs.get('hiddenNotices') || '{}';
+			try {
+				hiddenNotices = JSON.parse(hiddenNotices);
+			}
+			catch (e) {
+				Zotero.logError(e);
+				hiddenNotices = {};
+			}
+			
+			let id = messageElem.getAttribute('id');
+			let title = messageElem.getAttribute('title');
+			let text = messageElem.textContent;
+			let url = messageElem.getAttribute('infoURL');
+			let now = Math.round(Date.now() / 1000);
+			let thirtyDays = 86400 * 30;
+			
+			if (id) {
+				if (hiddenNotices[id] && hiddenNotices[id] > now) {
+					Zotero.debug("Not showing hidden notice " + id, 2);
+					Zotero.debug(text, 2);
+					return;
+				}
+			}
+			else {
+				Zotero.debug("CHECKING");
+				let exp = _hiddenNoticesWithoutIDs.get(text);
+				Zotero.debug(exp);
+				Zotero.debug(now);
+				if (exp && exp > now) {
+					Zotero.debug("Not showing hidden notice", 2);
+					Zotero.debug(text, 2);
+					return;
+				}
+			}
+			
+			setTimeout(() => {
+				Zotero.debug(text, 2);
+				
+				var ps = Services.prompt;
+				var buttonFlags = ps.BUTTON_POS_0 * ps.BUTTON_TITLE_OK
+					+ ps.BUTTON_POS_1 * ps.BUTTON_TITLE_IS_STRING;
+				var checkState = {};
+				var index = ps.confirmEx(
+					null,
+					title || Zotero.getString('general.warning'),
+					text,
+					buttonFlags,
+					"",
+					// Show "More Information" button if repo includes a URL
+					url ? Zotero.getString('general.moreInformation') : "",
+					"",
+					// Show "Don't show again for 30 days" if repo includes an id
+					id ? Zotero.getString('general.dontShowAgainFor', 30, 30) : null,
+					checkState
+				);
+				
+				if (index == 1) {
+					setTimeout(function () {
+						Zotero.launchURL(url);
+					}, 1);
+				}
+				// Handle "Don't show again for 30 days" checkbox
+				if (id) {
+					if (checkState.value) {
+						hiddenNotices[id] = now + thirtyDays;
+					}
+					// If not checked, still don't show again for a day
+					else {
+						hiddenNotices[id] = now + 86400;
+					}
+					// Remove expired hidden notices
+					for (let i in hiddenNotices) {
+						if (hiddenNotices[i] < now) {
+							delete hiddenNotices[i];
+						}
+					}
+					if (Object.keys(hiddenNotices).length) {
+						Zotero.Prefs.set('hiddenNotices', JSON.stringify(hiddenNotices));
+					}
+					else {
+						Zotero.Prefs.clear('hiddenNotices');
+					}
+				}
+				else {
+					// Don't show id-less messages again for a day
+					_hiddenNoticesWithoutIDs.set(text, now + 86400);
+				}
+			}, 500);
+		}
+		catch (e) {
+			Zotero.logError(e);
+		}
+	}
+	
+	
 	/**
 	* Set the interval between repository queries
 	*
diff --git a/test/tests/schemaTest.js b/test/tests/schemaTest.js
index 53b392d638..ade697d5d4 100644
--- a/test/tests/schemaTest.js
+++ b/test/tests/schemaTest.js
@@ -240,6 +240,159 @@ describe("Zotero.Schema", function() {
 	});
 	
 	
+	describe("Repository Check", function () {
+		describe("Notices", function () {
+			var win;
+			var server;
+			
+			before(async function () {
+				win = await loadZoteroPane();
+			});
+			
+			beforeEach(function () {
+				Zotero.HTTP.mock = sinon.FakeXMLHttpRequest;
+				server = sinon.fakeServer.create();
+				server.autoRespond = true;
+			});
+			
+			afterEach(function () {
+				Zotero.Prefs.clear('hiddenNotices');
+			});
+			
+			after(function () {
+				win.close();
+				Zotero.HTTP.mock = null;
+			});
+			
+			function createResponseWithMessage(message) {
+				server.respond(function (req) {
+					if (req.method != "POST" || !req.url.includes('/repo/updated')) {
+						return;
+					}
+					req.respond(
+						200,
+						{
+							"Content-Type": "application/xml"
+						},
+						'<xml>'
+							+ '<currentTime>1630219842</currentTime>'
+							+ message
+							+ '</xml>'
+					);
+				});
+			}
+			
+			it("should show dialog if repo returns a message", async function () {
+				createResponseWithMessage(
+					`<message infoURL="https://example.com">This is a warning</message>`
+				);
+				
+				var promise = waitForDialog(function (dialog) {
+					var html = dialog.document.documentElement.outerHTML;
+					assert.include(html, "This is a warning");
+				});
+				await Zotero.Schema.updateFromRepository(3);
+				await promise;
+				
+				// Don't show id-less message again for a day
+				var spy = sinon.spy(Zotero, 'debug');
+				await Zotero.Schema.updateFromRepository(3);
+				assert.notEqual(spy.args.findIndex(x => {
+					return typeof x[0] == 'string' && x[0].startsWith("Not showing hidden");
+				}), -1);
+				spy.restore();
+			});
+			
+			it("shouldn't show message with id again for 1 day even if not hidden", async function () {
+				var id = Zotero.Utilities.randomString();
+				createResponseWithMessage(
+					`<message id="${id}" infoURL="https://example.com">This is a warning</message>`
+				);
+				
+				var promise = waitForDialog();
+				await Zotero.Schema.updateFromRepository(3);
+				await promise;
+				
+				// Make sure notice is hidden for 1 day
+				var hiddenNotices;
+				var tries = 0;
+				var ttl = 86400;
+				while (tries < 100) {
+					tries++;
+					hiddenNotices = Zotero.Prefs.get('hiddenNotices');
+					if (!hiddenNotices) {
+						await Zotero.Promise.delay(10);
+						continue;
+					}
+					hiddenNotices = JSON.parse(hiddenNotices);
+					assert.property(hiddenNotices, id);
+					assert.approximately(hiddenNotices[id], Math.round(Date.now() / 1000) + ttl, 10);
+					break;
+				}
+			});
+			
+			it("shouldn't show message with id again for 30 days", async function () {
+				var id = Zotero.Utilities.randomString();
+				createResponseWithMessage(
+					`<message id="${id}" infoURL="https://example.com">This is a warning</message>`
+				);
+				
+				var promise = waitForDialog(function (dialog) {
+					var doc = dialog.document;
+					var innerHTML = doc.documentElement.innerHTML;
+					assert.include(innerHTML, "This is a warning");
+					assert.include(innerHTML, Zotero.getString('general.dontShowAgainFor', 30, 30));
+					// Check "Don't show again"
+					doc.getElementById('checkbox').click();
+				});
+				await Zotero.Schema.updateFromRepository(3);
+				await promise;
+				
+				// Make sure notice is hidden for 30 days
+				var hiddenNotices;
+				var tries = 0;
+				var ttl = 30 * 86400;
+				while (tries < 100) {
+					tries++;
+					hiddenNotices = Zotero.Prefs.get('hiddenNotices');
+					if (!hiddenNotices) {
+						await Zotero.Promise.delay(10);
+						continue;
+					}
+					hiddenNotices = JSON.parse(hiddenNotices);
+					assert.property(hiddenNotices, id);
+					assert.approximately(hiddenNotices[id], Math.round(Date.now() / 1000) + ttl, 10);
+					break;
+				}
+			});
+			
+			it("shouldn't show message with id if before expiration", async function () {
+				var id = Zotero.Utilities.randomString();
+				createResponseWithMessage(
+					`<message id="${id}" infoURL="https://example.com">This is a warning</message>`
+				);
+				
+				// Set expiration for 30 days from now
+				var ttl = 30 * 86400;
+				Zotero.Prefs.set(
+					'hiddenNotices',
+					JSON.stringify({
+						[id]: Math.round(Date.now() / 1000) + ttl
+					})
+				);
+				
+				// Message should be hidden
+				var spy = sinon.spy(Zotero, 'debug');
+				await Zotero.Schema.updateFromRepository(3);
+				assert.notEqual(spy.args.findIndex(x => {
+					return typeof x[0] == 'string' && x[0].startsWith("Not showing hidden");
+				}), -1);
+				spy.restore();
+			});
+		});
+	});
+	
+	
 	describe("#integrityCheck()", function () {
 		before(function* () {
 			yield resetDB({