Hello. Thank you for contacting the Toolset support.
This is known issue and this is due to the plugin name changed. The plugin name "ultimate-addons-for-gutenberg" changed to "Spectra Gutenberg Blocks – Website Builder for the Block Editor"
- https://wordpress.org/plugins/ultimate-addons-for-gutenberg/
You can install the above plugin on your site. Once you install it, do not activate it.
What you should try to do is, you will have to modify the plugin file with few lines.
- You should go to (use any editor to edit the plugin files): plugins/ultimate-addons-for-gutenberg
- open the file "ultimate-addons-for-gutenberg.php" in any file editor (install any file manager plugin to edit the plugin file)
- Replace the following line from: