diff --git a/src/classes/site.ts b/src/classes/site.ts
index 2b46c8e86..f24809ec9 100644
--- a/src/classes/site.ts
+++ b/src/classes/site.ts
@@ -1061,7 +1061,7 @@ export class CoreSite {
                 }
 
                 if (alertMessage) {
-                    let alert = this.domUtils.showAlert('core.notice', alertMessage, null, 3000);
+                    let alert = this.domUtils.showAlert('core.notice', alertMessage, undefined, 3000);
                     alert.onDidDismiss(() => {
                         if (inApp) {
                             resolve(this.utils.openInApp(url, options));
diff --git a/src/classes/sqlitedb.ts b/src/classes/sqlitedb.ts
index 6b718eca8..04f9fa6f6 100644
--- a/src/classes/sqlitedb.ts
+++ b/src/classes/sqlitedb.ts
@@ -262,7 +262,7 @@ export class SQLiteDB {
      * @return {Promise<any>} Promise resolved when done.
      */
     deleteRecords(table: string, conditions?: object) : Promise<any> {
-        if (conditions === null) {
+        if (conditions === null || typeof conditions == 'undefined') {
             // No conditions, delete the whole table.
             return this.execute(`DELETE FROM TABLE ${table}`);
         }
@@ -674,10 +674,10 @@ export class SQLiteDB {
      */
     normaliseLimitFromNum(limitFrom: any, limitNum: any) : number[] {
         // We explicilty treat these cases as 0.
-        if (limitFrom === null || limitFrom === '' || limitFrom === -1) {
+        if (typeof limitFrom == 'undefined' || limitFrom === null || limitFrom === '' || limitFrom === -1) {
             limitFrom = 0;
         }
-        if (limitNum === null || limitNum === '' || limitNum === -1) {
+        if (typeof limitNum == 'undefined' || limitNum === null || limitNum === '' || limitNum === -1) {
             limitNum = 0;
         }
 
diff --git a/src/core/emulator/providers/local-notifications.ts b/src/core/emulator/providers/local-notifications.ts
index 35c1b6561..d7eef13db 100644
--- a/src/core/emulator/providers/local-notifications.ts
+++ b/src/core/emulator/providers/local-notifications.ts
@@ -261,7 +261,7 @@ export class LocalNotificationsMock extends LocalNotifications {
      * @returns {Promise<Array<ILocalNotification>>}
      */
     getAll(): Promise<Array<ILocalNotification>> {
-        return Promise.resolve(this.getNotifications(null, true, true));
+        return Promise.resolve(this.getNotifications(undefined, true, true));
     }
 
     /**
@@ -292,7 +292,7 @@ export class LocalNotificationsMock extends LocalNotifications {
      * @returns {Promise<Array<ILocalNotification>>}
      */
     getAllScheduled(): Promise<Array<ILocalNotification>> {
-        return Promise.resolve(this.getNotifications(null, true, false));
+        return Promise.resolve(this.getNotifications(undefined, true, false));
     }
 
     /**
@@ -301,7 +301,7 @@ export class LocalNotificationsMock extends LocalNotifications {
      * @returns {Promise<Array<ILocalNotification>>}
      */
     getAllTriggered(): Promise<Array<ILocalNotification>> {
-        return Promise.resolve(this.getNotifications(null, false, true));
+        return Promise.resolve(this.getNotifications(undefined, false, true));
     }
 
     /**
diff --git a/src/core/login/pages/email-signup/email-signup.ts b/src/core/login/pages/email-signup/email-signup.ts
index cd87027c3..dcf5a0f2e 100644
--- a/src/core/login/pages/email-signup/email-signup.ts
+++ b/src/core/login/pages/email-signup/email-signup.ts
@@ -71,7 +71,7 @@ export class CoreLoginEmailSignupPage {
         this.usernameErrors = this.loginHelper.getErrorMessages('core.login.usernamerequired');
         this.passwordErrors = this.loginHelper.getErrorMessages('core.login.passwordrequired');
         this.emailErrors = this.loginHelper.getErrorMessages('core.login.missingemail');
-        this.email2Errors = this.loginHelper.getErrorMessages('core.login.missingemail', null, 'core.login.emailnotmatch');
+        this.email2Errors = this.loginHelper.getErrorMessages('core.login.missingemail', undefined, 'core.login.emailnotmatch');
         this.policyErrors = this.loginHelper.getErrorMessages('core.login.policyagree');
     }
 
diff --git a/src/core/login/providers/helper.ts b/src/core/login/providers/helper.ts
index d6baa15d7..8b6314010 100644
--- a/src/core/login/providers/helper.ts
+++ b/src/core/login/providers/helper.ts
@@ -690,7 +690,7 @@ export class CoreLoginHelperProvider {
      * @param {string} error Error message.
      */
     openChangePassword(siteUrl: string, error: string) : void {
-        let alert = this.domUtils.showAlert(this.translate.instant('core.notice'), error, null, 3000);
+        let alert = this.domUtils.showAlert(this.translate.instant('core.notice'), error, undefined, 3000);
         alert.onDidDismiss(() => {
             this.utils.openInApp(siteUrl + '/login/change_password.php');
         });
diff --git a/src/providers/sites.ts b/src/providers/sites.ts
index ff9877eec..00311e8bc 100644
--- a/src/providers/sites.ts
+++ b/src/providers/sites.ts
@@ -1043,7 +1043,7 @@ export class CoreSitesProvider {
             return Promise.resolve();
         }
 
-        return site.getConfig(null, true);
+        return site.getConfig(undefined, true);
     }
 
     /**
diff --git a/src/providers/utils/dom.ts b/src/providers/utils/dom.ts
index 59d48c641..719e68a5c 100644
--- a/src/providers/utils/dom.ts
+++ b/src/providers/utils/dom.ts
@@ -712,7 +712,7 @@ export class CoreDomUtilsProvider {
         }
 
         let message = this.textUtils.decodeHTML(needsTranslate ? this.translate.instant(error) : error);
-        return this.showAlert(this.getErrorTitle(message), message, null, autocloseTime);
+        return this.showAlert(this.getErrorTitle(message), message, undefined, autocloseTime);
     }
 
     /**