The block editor shows a JavaScript error or the sidebar is empty

Symptom

The Visual Portfolio block renders as an error in the editor, or its settings panels open empty.

Cause

• A server module truncating large scripts. Apache mod_substitute has a line length limit that cut the block’s script; this was worked around in 3.7.0.
• A JavaScript optimizer combining or minifying editor scripts.
• A very old free plugin installed next to Pro.
• WordPress 7.2 with a plugin version before 3.9.0. The Settings panel of the Posts source opens empty.

Fix

1. Update the plugin. Version 3.9.0 or newer is needed on WordPress 7.2.
2. Exclude /wp-admin/ and the visual-portfolio scripts from JavaScript optimization.
3. Update or remove the old free plugin.

The browser console names the script that failed, which tells you which of the causes it is.