Update to 20.0.0RC2 fails from beta4. Could not copy "/data/nextcloud/apps/dashboard/js/dashboard.js.map" #23068

Updater.log

Could not copy "/data/nextcloud/apps/dashboard/js/dashboard.js.map" to "/data/nextcloud/data/updater-ochxgtum9iy3/backups/nextcloud-20.0.0.6/apps/dashboard/js/dashboard.js.map"

Now the webui displays: It looks like you are trying to reinstall your Nextcloud. However the file CAN_INSTALL is missing from your config directory. Please create the file CAN_INSTALL in your config folder to continue.

Server configuration detail
Operating system: Linux 5.8.5-meson64 #20.08.1 SMP PREEMPT Tue Sep 1 18:47:20 CEST 2020 aarch64
Webserver: Apache (fpm-fcgi)
Database: mysql 10.3.23
PHP version: 7.3.19-1~deb10u1

Modules loaded: Core, date, libxml, openssl, pcre, zlib, filter, hash, Reflection, SPL, session, sodium, standard, cgi-fcgi, mysqlnd, PDO, xml, bcmath, bz2, calendar, ctype, curl, dom, mbstring, fileinfo, ftp, gd, gettext, gmp, iconv, igbinary, imagick, intl, json, ldap, exif, mysqli, pdo_mysql, Phar, posix, readline, redis, shmop, SimpleXML, smbclient, sockets, sysvmsg, sysvsem, sysvshm, tokenizer, wddx, xmlreader, xmlwriter, xsl, zip, libsmbclient, Zend OPcache

Nextcloud version: 20.0.0 Beta 4 - 20.0.0.6

Updated from an older Nextcloud

Enabled:

• accessibility: 1.6.0
• activity: 2.13.1
• admin_audit: 1.10.0
• apporder: 0.11.0
• bookmarks: 3.3.4
• breezedark: 19.0.4
• calendar: 2.1.2
• cloud_federation_api: 1.3.0
• cms_pico: 1.0.10
• comments: 1.10.0
• contactsinteraction: 1.1.0
• cpanelmailsync: 0.0.7
• customproperties: 1.0.1
• dashboard: 7.0.0
• dav: 1.16.0
• deck: 1.1.0-beta2
• end_to_end_encryption: 1.6.2
• external: 3.7.0
• federatedfilesharing: 1.10.1
• federation: 1.10.1
• files: 1.15.0
• files_external: 1.11.1
• files_pdfviewer: 2.0.1
• files_rightclick: 0.17.0
• files_sharing: 1.12.0
• files_trashbin: 1.10.1
• files_versions: 1.13.0
• files_videoplayer: 1.9.0
• firstrunwizard: 2.9.0
• flow_notifications: 1.0.1
• globalsiteselector: 1.3.0
• integration_mastodon: 0.0.3
• integration_reddit: 0.0.2
• login_notes: 0.3.0
• logreader: 2.5.0
• lookup_server_connector: 1.8.0
• mail: 1.4.1
• news: 14.2.2
• nextcloud_announcements: 1.9.0
• nextcloudpi: 0.0.1
• notes: 3.6.4
• notifications: 2.8.0
• oauth2: 1.8.0
• password_policy: 1.10.1
• photos: 1.2.0
• polls: 1.5.1
• previewgenerator: 102.2.0
• privacy: 1.4.0
• provisioning_api: 1.10.0
• qownnotesapi: 20.9.0
• recommendations: 0.8.0
• riotchat: 0.6.10
• serverinfo: 1.10.0
• settings: 1.2.0
• sharebymail: 1.10.0
• sharingpath: 0.2.5
• side_menu: 1.16.0
• spreed: 10.0.0-rc.2
• support: 1.3.0
• survey_client: 1.8.0
• systemtags: 1.10.0
• talk_matterbridge: 1.18.3
• tasks: 0.13.3
• text: 3.1.0
• theming: 1.11.0
• twofactor_backupcodes: 1.9.0
• updatenotification: 1.10.0
• user_status: 1.0.0
• viewer: 1.4.0
• weather_status: 1.0.0
• workflow_script: 1.5.0
• workflowengine: 2.2.0