diff --git a/core/src/OC/backbone-webdav.js b/core/src/OC/backbone-webdav.js
deleted file mode 100644
index 09e16befe45..00000000000
--- a/core/src/OC/backbone-webdav.js
+++ /dev/null
@@ -1,355 +0,0 @@
-/**
- * SPDX-FileCopyrightText: 2019 Nextcloud GmbH and Nextcloud contributors
- * SPDX-License-Identifier: AGPL-3.0-or-later
- */
-
-import { dav } from 'davclient.js'
-import _ from 'underscore'
-import logger from '../logger.js'
-
-const methodMap = {
-	create: 'POST',
-	update: 'PROPPATCH',
-	patch: 'PROPPATCH',
-	delete: 'DELETE',
-	read: 'PROPFIND',
-}
-
-/**
- * Throw an error when a URL is needed, and none is supplied.
- */
-function urlError() {
-	throw new Error('A "url" property or function must be specified')
-}
-
-/**
- * Convert a single propfind result to JSON
- *
- * @param {object} result
- * @param {object} davProperties properties mapping
- */
-function parsePropFindResult(result, davProperties) {
-	if (_.isArray(result)) {
-		return _.map(result, function(subResult) {
-			return parsePropFindResult(subResult, davProperties)
-		})
-	}
-	const props = {
-		href: result.href,
-	}
-
-	_.each(result.propStat, function(propStat) {
-		if (propStat.status !== 'HTTP/1.1 200 OK') {
-			return
-		}
-
-		for (const key in propStat.properties) {
-			let propKey = key
-			if (key in davProperties) {
-				propKey = davProperties[key]
-			}
-			props[propKey] = propStat.properties[key]
-		}
-	})
-
-	if (!props.id) {
-		// parse id from href
-		props.id = parseIdFromLocation(props.href)
-	}
-
-	return props
-}
-
-/**
- * Parse ID from location
- *
- * @param {string} url url
- * @return {string} id
- */
-function parseIdFromLocation(url) {
-	const queryPos = url.indexOf('?')
-	if (queryPos > 0) {
-		url = url.substr(0, queryPos)
-	}
-
-	const parts = url.split('/')
-	let result
-	do {
-		result = parts[parts.length - 1]
-		parts.pop()
-		// note: first result can be empty when there is a trailing slash,
-		// so we take the part before that
-	} while (!result && parts.length > 0)
-
-	return result
-}
-
-/**
- *
- * @param {number} status
- */
-function isSuccessStatus(status) {
-	return status >= 200 && status <= 299
-}
-
-/**
- *
- * @param attrs
- * @param davProperties
- */
-function convertModelAttributesToDavProperties(attrs, davProperties) {
-	const props = {}
-	let key
-	for (key in attrs) {
-		let changedProp = davProperties[key]
-		let value = attrs[key]
-		if (!changedProp) {
-			logger.warn('No matching DAV property for property "' + key)
-			changedProp = key
-		}
-		if (_.isBoolean(value) || _.isNumber(value)) {
-			// convert to string
-			value = '' + value
-		}
-		props[changedProp] = value
-	}
-	return props
-}
-
-/**
- *
- * @param client
- * @param options
- * @param model
- * @param headers
- */
-function callPropFind(client, options, model, headers) {
-	return client.propFind(
-		options.url,
-		_.values(options.davProperties) || [],
-		options.depth,
-		headers,
-	).then(function(response) {
-		if (isSuccessStatus(response.status)) {
-			if (_.isFunction(options.success)) {
-				const propsMapping = _.invert(options.davProperties)
-				const results = parsePropFindResult(response.body, propsMapping)
-				if (options.depth > 0) {
-					// discard root entry
-					results.shift()
-				}
-
-				options.success(results)
-			}
-		} else if (_.isFunction(options.error)) {
-			options.error(response)
-		}
-	})
-}
-
-/**
- *
- * @param client
- * @param options
- * @param model
- * @param headers
- */
-function callPropPatch(client, options, model, headers) {
-	return client.propPatch(
-		options.url,
-		convertModelAttributesToDavProperties(model.changed, options.davProperties),
-		headers,
-	).then(function(result) {
-		if (isSuccessStatus(result.status)) {
-			if (_.isFunction(options.success)) {
-				// pass the object's own values because the server
-				// does not return the updated model
-				options.success(model.toJSON())
-			}
-		} else if (_.isFunction(options.error)) {
-			options.error(result)
-		}
-	})
-}
-
-/**
- *
- * @param client
- * @param options
- * @param model
- * @param headers
- */
-function callMkCol(client, options, model, headers) {
-	// call MKCOL without data, followed by PROPPATCH
-	return client.request(
-		options.type,
-		options.url,
-		headers,
-		null,
-	).then(function(result) {
-		if (!isSuccessStatus(result.status)) {
-			if (_.isFunction(options.error)) {
-				options.error(result)
-			}
-			return
-		}
-
-		callPropPatch(client, options, model, headers)
-	})
-}
-
-/**
- *
- * @param client
- * @param options
- * @param model
- * @param headers
- */
-function callMethod(client, options, model, headers) {
-	headers['Content-Type'] = 'application/json'
-	return client.request(
-		options.type,
-		options.url,
-		headers,
-		options.data,
-	).then(function(result) {
-		if (!isSuccessStatus(result.status)) {
-			if (_.isFunction(options.error)) {
-				options.error(result)
-			}
-			return
-		}
-
-		if (_.isFunction(options.success)) {
-			if (options.type === 'PUT' || options.type === 'POST' || options.type === 'MKCOL') {
-				// pass the object's own values because the server
-				// does not return anything
-				const responseJson = result.body || model.toJSON()
-				const locationHeader = result.xhr.getResponseHeader('Content-Location')
-				if (options.type === 'POST' && locationHeader) {
-					responseJson.id = parseIdFromLocation(locationHeader)
-				}
-				options.success(responseJson)
-				return
-			}
-			// if multi-status, parse
-			if (result.status === 207) {
-				const propsMapping = _.invert(options.davProperties)
-				options.success(parsePropFindResult(result.body, propsMapping))
-			} else {
-				options.success(result.body)
-			}
-		}
-	})
-}
-
-/**
- *
- * @param options
- * @param model
- */
-export function davCall(options, model) {
-	const client = new dav.Client({
-		baseUrl: options.url,
-		xmlNamespaces: _.extend({
-			'DAV:': 'd',
-			'http://owncloud.org/ns': 'oc',
-		}, options.xmlNamespaces || {}),
-	})
-	client.resolveUrl = function() {
-		return options.url
-	}
-	const headers = _.extend({
-		'X-Requested-With': 'XMLHttpRequest',
-		requesttoken: OC.requestToken,
-	}, options.headers)
-	if (options.type === 'PROPFIND') {
-		return callPropFind(client, options, model, headers)
-	} else if (options.type === 'PROPPATCH') {
-		return callPropPatch(client, options, model, headers)
-	} else if (options.type === 'MKCOL') {
-		return callMkCol(client, options, model, headers)
-	} else {
-		return callMethod(client, options, model, headers)
-	}
-}
-
-/**
- * DAV transport
- *
- * @param Backbone
- */
-export function davSync(Backbone) {
-	return (method, model, options) => {
-		const params = { type: methodMap[method] || method }
-		const isCollection = (model instanceof Backbone.Collection)
-
-		if (method === 'update') {
-		// if a model has an inner collection, it must define an
-		// attribute "hasInnerCollection" that evaluates to true
-			if (model.hasInnerCollection) {
-			// if the model itself is a Webdav collection, use MKCOL
-				params.type = 'MKCOL'
-			} else if (model.usePUT || (model.collection && model.collection.usePUT)) {
-			// use PUT instead of PROPPATCH
-				params.type = 'PUT'
-			}
-		}
-
-		// Ensure that we have a URL.
-		if (!options.url) {
-			params.url = _.result(model, 'url') || urlError()
-		}
-
-		// Ensure that we have the appropriate request data.
-		// eslint-disable-next-line eqeqeq
-		if (options.data == null && model && (method === 'create' || method === 'update' || method === 'patch')) {
-			params.data = JSON.stringify(options.attrs || model.toJSON(options))
-		}
-
-		// Don't process data on a non-GET request.
-		if (params.type !== 'PROPFIND') {
-			params.processData = false
-		}
-
-		if (params.type === 'PROPFIND' || params.type === 'PROPPATCH') {
-			let davProperties = model.davProperties
-			if (!davProperties && model.model) {
-			// use dav properties from model in case of collection
-				davProperties = model.model.prototype.davProperties
-			}
-			if (davProperties) {
-				if (_.isFunction(davProperties)) {
-					params.davProperties = davProperties.call(model)
-				} else {
-					params.davProperties = davProperties
-				}
-			}
-
-			params.davProperties = _.extend(params.davProperties || {}, options.davProperties)
-
-			if (_.isUndefined(options.depth)) {
-				if (isCollection) {
-					options.depth = 1
-				} else {
-					options.depth = 0
-				}
-			}
-		}
-
-		// Pass along `textStatus` and `errorThrown` from jQuery.
-		const error = options.error
-		options.error = function(xhr, textStatus, errorThrown) {
-			options.textStatus = textStatus
-			options.errorThrown = errorThrown
-			if (error) {
-				error.call(options.context, xhr, textStatus, errorThrown)
-			}
-		}
-
-		// Make the request, allowing the user to override any Ajax options.
-		const xhr = options.xhr = Backbone.davCall(_.extend(params, options), model)
-		model.trigger('request', model, xhr, options)
-		return xhr
-	}
-}
diff --git a/core/src/OC/backbone.js b/core/src/OC/backbone.js
deleted file mode 100644
index 08520e278f6..00000000000
--- a/core/src/OC/backbone.js
+++ /dev/null
@@ -1,17 +0,0 @@
-/**
- * SPDX-FileCopyrightText: 2019 Nextcloud GmbH and Nextcloud contributors
- * SPDX-License-Identifier: AGPL-3.0-or-later
- */
-
-import VendorBackbone from 'backbone'
-import { davCall, davSync } from './backbone-webdav.js'
-
-const Backbone = VendorBackbone.noConflict()
-
-// Patch Backbone for DAV
-Object.assign(Backbone, {
-	davCall,
-	davSync: davSync(Backbone),
-})
-
-export default Backbone
diff --git a/core/src/OC/index.js b/core/src/OC/index.js
index f5ff7eba61c..5270c879e82 100644
--- a/core/src/OC/index.js
+++ b/core/src/OC/index.js
@@ -29,7 +29,6 @@ import logger from '../logger.js'
 import { isUserAdmin } from './admin.js'
 import { appConfig } from './appconfig.js'
 import appswebroots from './appswebroots.js'
-import Backbone from './backbone.js'
 import { getCapabilities } from './capabilities.js'
 import Config from './config.js'
 import {
@@ -86,7 +85,6 @@ export default {
 	 */
 	appConfig,
 	appswebroots,
-	Backbone,
 	config: Config,
 	/**
 	 * Currently logged in user or null if none
diff --git a/core/src/globals.js b/core/src/globals.js
index 01569fef018..b3ef3802bbf 100644
--- a/core/src/globals.js
+++ b/core/src/globals.js
@@ -4,8 +4,6 @@
  */
 
 /* eslint-disable @nextcloud/no-deprecations */
-// END TODO
-import Backbone from 'backbone'
 import ClipboardJS from 'clipboard'
 import { dav } from 'davclient.js'
 import Handlebars from 'handlebars'
@@ -83,9 +81,8 @@ function setDeprecatedProp(global, cb, msg) {
 	})
 }
 
-window._ = _
 setDeprecatedProp(['$', 'jQuery'], () => $, 'The global jQuery is deprecated. It will be removed in a later versions without another warning. Please ship your own.')
-setDeprecatedProp('Backbone', () => Backbone, 'please ship your own, this will be removed in Nextcloud 20')
+setDeprecatedProp(['_'], () => _, 'The global underscore is deprecated. It will be removed in a later versions without another warning. Please ship your own.')
 setDeprecatedProp(['Clipboard', 'ClipboardJS'], () => ClipboardJS, 'please ship your own, this will be removed in Nextcloud 20')
 window.dav = dav
 setDeprecatedProp('Handlebars', () => Handlebars, 'please ship your own, this will be removed in Nextcloud 20')