diff --git a/src/appdb.js b/src/appdb.js
index 9dadd603c..698382bc9 100644
--- a/src/appdb.js
+++ b/src/appdb.js
@@ -21,8 +21,7 @@ exports = module.exports = {
     getAppIdByAddonConfigValue: getAppIdByAddonConfigValue,
 
     setHealth: setHealth,
-    setInstallationCommand: setInstallationCommand,
-    setRunCommand: setRunCommand,
+    setTask: setTask,
     getAppStoreIds: getAppStoreIds,
 
     // installation codes (keep in sync in UI)
@@ -479,25 +478,12 @@ function setHealth(appId, health, healthTime, callback) {
     updateWithConstraints(appId, values, constraints, callback);
 }
 
-function setInstallationCommand(appId, installationState, values, callback) {
+function setTask(appId, values, callback) {
     assert.strictEqual(typeof appId, 'string');
-    assert.strictEqual(typeof installationState, 'string');
     assert.strictEqual(typeof values, 'object');
     assert.strictEqual(typeof callback, 'function');
 
-    values.installationState = installationState;
-    values.errorMessage = '';
-
-    updateWithConstraints(appId, values, `AND (installationState = "${exports.ISTATE_INSTALLED}" OR installationState = "${exports.ISTATE_ERROR}")`, callback);
-}
-
-function setRunCommand(appId, runState, callback) {
-    assert.strictEqual(typeof appId, 'string');
-    assert.strictEqual(typeof runState, 'string');
-    assert.strictEqual(typeof callback, 'function');
-
-    var values = { runState: runState };
-    updateWithConstraints(appId, values, `AND installationState = "${exports.ISTATE_INSTALLED}"`, callback);
+    updateWithConstraints(appId, values, 'AND taskId IS NULL', callback);
 }
 
 function getAppStoreIds(callback) {
diff --git a/src/apps.js b/src/apps.js
index b37f2d581..252c7f02b 100644
--- a/src/apps.js
+++ b/src/apps.js
@@ -322,17 +322,17 @@ function validateDataDir(dataDir) {
     return null;
 }
 
-function getDuplicateErrorDetails(error, location, domainObject, portBindings, alternateDomains) {
-    assert.strictEqual(error.reason, DatabaseError.ALREADY_EXISTS);
+function getDuplicateErrorDetails(errorMessage, location, domainObject, portBindings, alternateDomains) {
+    assert.strictEqual(typeof errorMessage, 'string');
     assert.strictEqual(typeof location, 'string');
     assert.strictEqual(typeof domainObject, 'object');
     assert.strictEqual(typeof portBindings, 'object');
     assert(Array.isArray(alternateDomains));
 
-    var match = error.message.match(/ER_DUP_ENTRY: Duplicate entry '(.*)' for key '(.*)'/);
+    var match = errorMessage.match(/ER_DUP_ENTRY: Duplicate entry '(.*)' for key '(.*)'/);
     if (!match) {
-        debug('Unexpected SQL error message.', error);
-        return new AppsError(AppsError.INTERNAL_ERROR, error);
+        debug('Unexpected SQL error message.', errorMessage);
+        return new AppsError(AppsError.INTERNAL_ERROR, new Error(errorMessage));
     }
 
     // check if the location or alternateDomains conflicts
@@ -576,15 +576,23 @@ function mailboxNameForLocation(location, manifest) {
     return (location ? location : manifest.title.toLowerCase().replace(/[^a-zA-Z0-9]/g, '')) + '.app';
 }
 
-function scheduleTask(appId, args, callback) {
+function scheduleTask(appId, args, values, callback) {
     assert.strictEqual(typeof appId, 'string');
     assert.strictEqual(typeof args, 'object');
+    assert.strictEqual(typeof values, 'object');
     assert.strictEqual(typeof callback, 'function');
 
+    assert(values.installationState || values.runState);
+
     tasks.add(tasks.TASK_APP, [ appId, args ], function (error, taskId) {
         if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, error));
 
-        appdb.update(appId, { taskId: taskId }, function (error) {
+        values.errorMessage = '';
+        values.taskId = taskId;
+
+        appdb.setTask(appId, values, function (error) {
+            if (error && error.reason === DatabaseError.ALREADY_EXISTS) return callback(new AppsError(AppsError.ALREADY_EXISTS, error.message));
+            if (error && error.reason === DatabaseError.NOT_FOUND) return callback(new AppsError(AppsError.BAD_STATE));
             if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, error));
 
             appTaskManager.scheduleTask(appId, taskId, function (error) {
@@ -713,7 +721,7 @@ function install(data, user, auditSource, callback) {
             };
 
             appdb.add(appId, appStoreId, manifest, location, domain, translatePortBindings(portBindings, manifest), data, function (error) {
-                if (error && error.reason === DatabaseError.ALREADY_EXISTS) return callback(getDuplicateErrorDetails(error, location, domainObject, portBindings, data.alternateDomains));
+                if (error && error.reason === DatabaseError.ALREADY_EXISTS) return callback(getDuplicateErrorDetails(error.message, location, domainObject, portBindings, data.alternateDomains));
                 if (error && error.reason === DatabaseError.NOT_FOUND) return callback(new AppsError(AppsError.NOT_FOUND, error.message));
                 if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, error));
 
@@ -728,7 +736,7 @@ function install(data, user, auditSource, callback) {
 
                     const restoreConfig = backupId ? { backupId: backupId, backupFormat: backupFormat } : null;
 
-                    scheduleTask(appId, { restoreConfig }, function (error, result) {
+                    scheduleTask(appId, { restoreConfig }, { installationState: appdb.ISTATE_PENDING_INSTALL }, function (error, result) {
                         if (error) return callback(error);
 
                         eventlog.add(eventlog.ACTION_APP_INSTALL, auditSource, { appId: appId, app: result });
@@ -750,9 +758,10 @@ function configure(appId, data, user, auditSource, callback) {
 
     get(appId, function (error, app) {
         if (error) return callback(error);
-        if (app.installationState !== appdb.ISTATE_INSTALLED && app.installationState !== appdb.ISTATE_ERROR) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState}`));
+        if (app.taskId) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState} / ${app.runState}`));
+
+        let domain, location, portBindings, values = { installationState: appdb.ISTATE_PENDING_CONFIGURE };
 
-        let domain, location, portBindings, values = { };
         if ('location' in data && 'domain' in data) {
             location = values.location = data.location.toLowerCase();
             domain = values.domain = data.domain.toLowerCase();
@@ -870,18 +879,13 @@ function configure(appId, data, user, auditSource, callback) {
 
             debug(`configure: id:${appId}`);
 
-            appdb.setInstallationCommand(appId, appdb.ISTATE_PENDING_CONFIGURE, values, function (error) {
-                if (error && error.reason === DatabaseError.ALREADY_EXISTS) return callback(getDuplicateErrorDetails(error, location, domainObject, portBindings, data.alternateDomains));
-                if (error && error.reason === DatabaseError.NOT_FOUND) return callback(new AppsError(AppsError.BAD_STATE));
-                if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, error));
+            scheduleTask(appId, { oldConfig: getAppConfig(app) }, values, function (error, result) {
+                if (error && error.reason === AppsError.ALREADY_EXISTS) error = getDuplicateErrorDetails(error.message, location, domainObject, portBindings, data.alternateDomains);
+                if (error) return callback(error);
 
-                scheduleTask(appId, { oldConfig: getAppConfig(app) }, function (error, result) {
-                    if (error) return callback(error);
+                eventlog.add(eventlog.ACTION_APP_CONFIGURE, auditSource, { appId: appId, app: result });
 
-                    eventlog.add(eventlog.ACTION_APP_CONFIGURE, auditSource, { appId: appId, app: result });
-
-                    callback(null, { taskId: result.taskId });
-                });
+                callback(null, { taskId: result.taskId });
             });
         });
     });
@@ -897,7 +901,7 @@ function update(appId, data, auditSource, callback) {
 
     get(appId, function (error, app) {
         if (error) return callback(error);
-        if (app.installationState !== appdb.ISTATE_INSTALLED && app.installationState !== appdb.ISTATE_ERROR) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState}`));
+        if (app.taskId) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState} / ${app.runState}`));
 
         downloadManifest(data.appStoreId, data.manifest, function (error, appStoreId, manifest) {
             if (error) return callback(error);
@@ -951,20 +955,15 @@ function update(appId, data, auditSource, callback) {
                 updateConfig.memoryLimit = updateConfig.manifest.memoryLimit;
             }
 
-            appdb.setInstallationCommand(appId, appdb.ISTATE_PENDING_UPDATE, { }, function (error) {
-                if (error && error.reason === DatabaseError.NOT_FOUND) return callback(new AppsError(AppsError.BAD_STATE)); // might be a bad guess
-                if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, error));
+            scheduleTask(appId, { updateConfig: updateConfig }, { installationState: appdb.ISTATE_PENDING_UPDATE }, function (error, result) {
+                if (error) return callback(error);
 
-                scheduleTask(appId, { updateConfig: updateConfig }, function (error, result) {
-                    if (error) return callback(error);
+                eventlog.add(eventlog.ACTION_APP_UPDATE, auditSource, { appId: appId, toManifest: manifest, fromManifest: app.manifest, force: data.force, app: app });
 
-                    eventlog.add(eventlog.ACTION_APP_UPDATE, auditSource, { appId: appId, toManifest: manifest, fromManifest: app.manifest, force: data.force, app: app });
+                // clear update indicator, if update fails, it will come back through the update checker
+                updateChecker.resetAppUpdateInfo(appId);
 
-                    // clear update indicator, if update fails, it will come back through the update checker
-                    updateChecker.resetAppUpdateInfo(appId);
-
-                    callback(null, { taskId: result.taskId });
-                });
+                callback(null, { taskId: result.taskId });
             });
         });
     });
@@ -1034,7 +1033,7 @@ function restore(appId, data, auditSource, callback) {
 
     get(appId, function (error, app) {
         if (error) return callback(error);
-        if (app.installationState !== appdb.ISTATE_INSTALLED && app.installationState !== appdb.ISTATE_ERROR) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState}`));
+        if (app.taskId) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState} / ${app.runState}`));
 
         // for empty or null backupId, use existing manifest to mimic a reinstall
         var func = data.backupId ? backups.get.bind(null, data.backupId) : function (next) { return next(null, { manifest: app.manifest }); };
@@ -1050,22 +1049,18 @@ function restore(appId, data, auditSource, callback) {
             error = checkManifestConstraints(backupInfo.manifest);
             if (error) return callback(error);
 
-            var values = {
+            let values = {
+                installationState: appdb.ISTATE_PENDING_RESTORE,
                 manifest: backupInfo.manifest
             };
 
-            appdb.setInstallationCommand(appId, appdb.ISTATE_PENDING_RESTORE, values, function (error) {
-                if (error && error.reason === DatabaseError.NOT_FOUND) return callback(new AppsError(AppsError.BAD_STATE)); // might be a bad guess
-                if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, error));
+            const restoreConfig = data.backupId ? { backupId: data.backupId, backupFormat: backupInfo.format, oldManifest: app.manifest } : null; // when null, apptask simply reinstalls
+            scheduleTask(appId, { restoreConfig }, values, function (error, result) {
+                if (error) return callback(error);
 
-                const restoreConfig = data.backupId ? { backupId: data.backupId, backupFormat: backupInfo.format, oldManifest: app.manifest } : null; // when null, apptask simply reinstalls
-                scheduleTask(appId, { restoreConfig }, function (error, result) {
-                    if (error) return callback(error);
+                eventlog.add(eventlog.ACTION_APP_RESTORE, auditSource, { app: app, backupId: backupInfo.id, fromManifest: app.manifest, toManifest: backupInfo.manifest });
 
-                    eventlog.add(eventlog.ACTION_APP_RESTORE, auditSource, { app: app, backupId: backupInfo.id, fromManifest: app.manifest, toManifest: backupInfo.manifest });
-
-                    callback(null, { taskId: result.taskId });
-                });
+                callback(null, { taskId: result.taskId });
             });
         });
     });
@@ -1161,7 +1156,7 @@ function clone(appId, data, user, auditSource, callback) {
                 };
 
                 appdb.add(newAppId, app.appStoreId, manifest, location, domain, translatePortBindings(portBindings, manifest), data, function (error) {
-                    if (error && error.reason === DatabaseError.ALREADY_EXISTS) return callback(getDuplicateErrorDetails(error, location, domainObject, portBindings, []));
+                    if (error && error.reason === DatabaseError.ALREADY_EXISTS) return callback(getDuplicateErrorDetails(error.message, location, domainObject, portBindings, []));
                     if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, error));
 
                     purchaseApp({ appId: newAppId, appstoreId: app.appStoreId, manifestId: manifest.id }, function (error) {
@@ -1169,7 +1164,7 @@ function clone(appId, data, user, auditSource, callback) {
 
                         const restoreConfig = { backupId: backupId, backupFormat: backupInfo.format };
 
-                        scheduleTask(newAppId, { restoreConfig }, function (error, result) {
+                        scheduleTask(newAppId, { restoreConfig }, { installationState: appdb.ISTATE_PENDING_CLONE }, function (error, result) {
                             if (error) return callback(error);
 
                             eventlog.add(eventlog.ACTION_APP_CLONE, auditSource, { appId: newAppId, oldAppId: appId, backupId: backupId, oldApp: app, newApp: result });
@@ -1192,7 +1187,7 @@ function uninstall(appId, auditSource, callback) {
 
     get(appId, function (error, app) {
         if (error) return callback(error);
-        if (app.installationState !== appdb.ISTATE_INSTALLED && app.installationState !== appdb.ISTATE_ERROR) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState}`));
+        if (app.taskId) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState} / ${app.runState}`));
 
         appstore.unpurchaseApp(appId, { appstoreId: app.appStoreId, manifestId: app.manifest.id }, function (error) {
             if (error && error.reason === AppstoreError.NOT_FOUND) return callback(new AppsError(AppsError.NOT_FOUND));
@@ -1201,17 +1196,12 @@ function uninstall(appId, auditSource, callback) {
             if (error && error.reason === AppstoreError.EXTERNAL_ERROR) return callback(new AppsError(AppsError.EXTERNAL_ERROR, error.message));
             if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, error));
 
-            appdb.update(appId, { installationState: appdb.ISTATE_PENDING_UNINSTALL }, function (error) {
-                if (error && error.reason === DatabaseError.NOT_FOUND) return callback(new AppsError(AppsError.NOT_FOUND, 'No such app'));
-                if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, error));
+            scheduleTask(appId, { /* args */ }, { installationState: appdb.ISTATE_PENDING_UNINSTALL }, function (error, result) {
+                if (error) return callback(error);
 
-                scheduleTask(appId, {}, function (error, result) {
-                    if (error) return callback(error);
+                eventlog.add(eventlog.ACTION_APP_UNINSTALL, auditSource, { appId: appId, app: result });
 
-                    eventlog.add(eventlog.ACTION_APP_UNINSTALL, auditSource, { appId: appId, app: result });
-
-                    callback(null, { taskId: result.taskId });
-                });
+                callback(null, { taskId: result.taskId });
             });
         });
     });
@@ -1225,15 +1215,9 @@ function start(appId, callback) {
 
     get(appId, function (error, app) {
         if (error) return callback(error);
-        if (app.installationState !== appdb.ISTATE_INSTALLED) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState}`));
-        if (app.runState !== appdb.RSTATE_STOPPED) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState}`));
+        if (app.taskId) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState} / ${app.runState}`));
 
-        appdb.setRunCommand(appId, appdb.RSTATE_PENDING_START, function (error) {
-            if (error && error.reason === DatabaseError.NOT_FOUND) return callback(new AppsError(AppsError.BAD_STATE)); // might be a bad guess
-            if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, error));
-
-            scheduleTask(appId, {}, callback);
-        });
+        scheduleTask(appId, { /* args */ }, { runState: appdb.RSTATE_PENDING_START }, callback);
     });
 }
 
@@ -1245,15 +1229,9 @@ function stop(appId, callback) {
 
     get(appId, function (error, app) {
         if (error) return callback(error);
-        if (app.installationState !== appdb.ISTATE_INSTALLED) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState}`));
-        if (app.runState !== appdb.RSTATE_RUNNING) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState}`));
+        if (app.taskId) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState} / ${app.runState}`));
 
-        appdb.setRunCommand(appId, appdb.RSTATE_PENDING_STOP, function (error) {
-            if (error && error.reason === DatabaseError.NOT_FOUND) return callback(new AppsError(AppsError.BAD_STATE)); // might be a bad guess
-            if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, error));
-
-            scheduleTask(appId, {}, callback);
-        });
+        scheduleTask(appId, { /* args */ }, { runState: appdb.RSTATE_PENDING_STOP }, callback);
     });
 }
 
@@ -1393,24 +1371,18 @@ function backup(appId, callback) {
     assert.strictEqual(typeof appId, 'string');
     assert.strictEqual(typeof callback, 'function');
 
-    appdb.exists(appId, function (error, exists) {
-        if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, error));
-        if (!exists) return callback(new AppsError(AppsError.NOT_FOUND));
+    get(appId, function (error, app) {
+        if (error) return callback(error);
+        if (app.taskId) return callback(new AppsError(AppsError.BAD_STATE, `Not allowed in this app state : ${app.installationState} / ${app.runState}`));
 
-        appdb.setInstallationCommand(appId, appdb.ISTATE_PENDING_BACKUP, function (error) {
-            if (error && error.reason === DatabaseError.NOT_FOUND) return callback(new AppsError(AppsError.BAD_STATE)); // might be a bad guess
-            if (error) return callback(new AppsError(AppsError.INTERNAL_ERROR, error));
+        scheduleTask(appId, { /* args */ }, { installationState: appdb.ISTATE_PENDING_BACKUP }, (error, result) => {
+            if (error) return callback(error);
 
-            scheduleTask(appId, { }, (error, result) => {
-                if (error) return callback(error);
-
-                callback(null, { taskId: result.taskId });
-            });
+            callback(null, { taskId: result.taskId });
         });
     });
 }
 
-
 function listBackups(page, perPage, appId, callback) {
     assert(typeof page === 'number' && page > 0);
     assert(typeof perPage === 'number' && perPage > 0);
@@ -1442,10 +1414,10 @@ function restoreInstalledApps(callback) {
 
                 debug(`marking ${app.fqdn} for restore using restore config ${JSON.stringify(restoreConfig)}`);
 
-                appdb.setInstallationCommand(app.id, appdb.ISTATE_PENDING_RESTORE, { restoreConfig: restoreConfig }, function (error) {
+                appdb.update(app.id, { taskId: null }, function (error) { // clear any stale taskId
                     if (error) debug(`Error marking ${app.fqdn} for restore: ${JSON.stringify(error)}`);
 
-                    scheduleTask(app.id, { restoreConfig }, () => iteratorDone()); // always succeed
+                    scheduleTask(app.id, { restoreConfig }, { installationState: appdb.ISTATE_PENDING_RESTORE }, () => iteratorDone()); // always succeed
                 });
             });
         }, callback);
@@ -1461,10 +1433,10 @@ function configureInstalledApps(callback) {
         async.map(apps, function (app, iteratorDone) {
             debug(`marking ${app.fqdn} for reconfigure`);
 
-            appdb.setInstallationCommand(app.id, appdb.ISTATE_PENDING_CONFIGURE, { }, function (error) {
+            appdb.update(app.id, { taskId: null }, function (error) { // clear any stale taskId
                 if (error) debug(`Error marking ${app.fqdn} for reconfigure: ${JSON.stringify(error)}`);
 
-                scheduleTask(app.id, { oldConfig: getAppConfig(app) }, () => iteratorDone()); // always succeed
+                scheduleTask(app.id, { oldConfig: getAppConfig(app) }, { installationState: appdb.ISTATE_PENDING_CONFIGURE },  () => iteratorDone()); // always succeed
             });
         }, callback);
     });