diff --git a/backend/init.js b/backend/init.js
new file mode 100644
index 000000000..9ac75bcb4
--- /dev/null
+++ b/backend/init.js
@@ -0,0 +1,25 @@
+import Logger from './logger';
+
+import {
+    deleteAllConnections,
+    deleteBadConnections
+} from './persistent/Connections.js';
+import {getSetting} from './settings.js';
+
+const setCSVStorageSize = require('./persistent/datastores/csv.js').setStorageSize;
+
+export default function init() {
+    try {
+        deleteBadConnections();
+    } catch (error) {
+        Logger.log(`Failed to delete bad connections: ${error.message}`);
+        deleteAllConnections();
+    }
+
+    try {
+        setCSVStorageSize(getSetting('CSV_STORAGE_SIZE'));
+    } catch (error) {
+        Logger.log(`Failed to get setting CSV_STORAGE_SIZE: ${error.message}`);
+        setCSVStorageSize(0);
+    }
+}
diff --git a/backend/persistent/Connections.js b/backend/persistent/Connections.js
index b6562143a..58c31cb07 100644
--- a/backend/persistent/Connections.js
+++ b/backend/persistent/Connections.js
@@ -5,6 +5,7 @@ import {assoc, dissoc, findIndex} from 'ramda';
 import uuid from 'uuid';
 import YAML from 'yamljs';
 import * as Datastores from './datastores/Datastores.js';
+import {DIALECTS} from '../../app/constants/constants.js';
 
 import {getSetting} from '../settings';
 
@@ -39,11 +40,32 @@ export function deleteConnectionById(id) {
     const connections = getConnections();
     const index = findIndex(connection => connection.id === id, connections);
     if (index > -1) {
+        Datastores.disconnect(connections[index]);
         connections.splice(index, 1);
         fs.writeFileSync(getSetting('CONNECTIONS_PATH'), YAML.stringify(connections, 4));
     }
 }
 
+export function deleteBadConnections() {
+    getConnections().forEach(connection => {
+        const {id, dialect} = connection;
+
+        const dialects = Object.getOwnPropertyNames(DIALECTS).map(k => DIALECTS[k]);
+
+        const isUnknownDialect = (dialects.indexOf(dialect) === -1);
+        if (isUnknownDialect) {
+            deleteConnectionById(id);
+        }
+    });
+}
+
+export function deleteAllConnections() {
+    if (!fs.existsSync(getSetting('STORAGE_PATH'))) {
+        createStoragePath();
+    }
+    fs.writeFileSync(getSetting('CONNECTIONS_PATH'), YAML.stringify([], 4));
+}
+
 export function getSanitizedConnections() {
     const connections = getConnections();
     return connections.map(cred => sanitize(cred));
@@ -60,7 +82,7 @@ export function saveConnection(connectionObject) {
     return connectionId;
 }
 
-export function validateConnection (connectionObject) {
+export function validateConnection(connectionObject) {
     return Datastores.connect(connectionObject).then(() => {
         return {};
     }).catch(err => {
diff --git a/backend/routes.js b/backend/routes.js
index 5af56b5f7..e386555a9 100644
--- a/backend/routes.js
+++ b/backend/routes.js
@@ -1,11 +1,11 @@
-var restify = require('restify');
-var CookieParser = require('restify-cookies');
+const restify = require('restify');
+const CookieParser = require('restify-cookies');
+const fetch = require('node-fetch');
+
 import * as fs from 'fs';
 import path from 'path';
 
 import * as Datastores from './persistent/datastores/Datastores.js';
-const setCSVStorageSize = require('./persistent/datastores/csv.js').setStorageSize;
-
 import {PlotlyOAuth} from './plugins/authorization.js';
 import {getQueries, getQuery, deleteQuery} from './persistent/Queries';
 import {
@@ -27,7 +27,7 @@ import {checkWritePermissions, newDatacache} from './persistent/PlotlyAPI.js';
 import {contains, keys, isEmpty, merge, pluck} from 'ramda';
 import {getCerts, timeoutFetchAndSaveCerts, setRenewalJob} from './certificates';
 import Logger from './logger';
-import fetch from 'node-fetch';
+import init from './init.js';
 
 export default class Servers {
     /*
@@ -36,12 +36,7 @@ export default class Servers {
      * The httpsServer starts when certificates have been created.
      */
     constructor(args = {createCerts: true, startHttps: true, isElectron: false}) {
-        try {
-            setCSVStorageSize(getSetting('CSV_STORAGE_SIZE'));
-        } catch (error) {
-            Logger.log(`Failed to get setting CSV_STORAGE_SIZE: ${error.message}`);
-            setCSVStorageSize(0);
-        }
+        init();
 
         this.httpServer = {
             port: null,