What is the problem?
I have a DNS A entry routing octoprint.<my domain>.net to my public IP.
On my Apache server, I have set up virtual hosts for octoprint.<my domain>.net
<VirtualHost *:80>
ServerName octoprint.<my domain>.net
ServerAdmin <my email>
ProxyPass / http://localhost:5000/
ProxyPassReverse / http://localhost:5000/
ProxyPreserveHost On
ErrorLog ${APACHE_LOG_DIR}/octoprint.error.log
CustomLog ${APACHE_LOG_DIR}/octoprint.access.log combined
RewriteEngine on
RewriteCond %{SERVER_NAME} =octoprint.<my domain>.net
RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [END,NE,R=permanent]
</VirtualHost>
<IfModule mod_ssl.c>
<VirtualHost *:443>
ServerName octoprint.<my domain>.net
ServerAdmin <my email>
ProxyPass / http://localhost:5000/
ProxyPassReverse / http://localhost:5000/
ProxyPreserveHost On
ErrorLog ${APACHE_LOG_DIR}/octoprint.error.log
CustomLog ${APACHE_LOG_DIR}/octoprint.access.log combined
SSLCertificateFile /etc/letsencrypt/live/octoprint.<my domain>.net/fullchain.pem
SSLCertificateKeyFile /etc/letsencrypt/live/octoprint.<my domain>.net/privkey.pem
Include /etc/letsencrypt/options-ssl-apache.conf
</VirtualHost>
</IfModule>
Everything is working fine with octoprint v1.8.2 (I can browse to https://octoprint.<my domain>.net)
With octoprint v1.8.2, HTTP is ok with octoprint v1.8.7
http screenshot
but HTTPS does not work
https screenshot
What did you already try to solve it?
Downgrade to v1.8.2 -> OK
Disable HTTPS virtual host definition in Apache -> OK, but no more HTTPS for sure 
Tried to understand the browser console message : Issue with packed_core.js (see https screenshot)
Logs (syslog, dmesg, ... no logs, no support)
No octoprint*.log* anywhere on the server...
Additional information about your network
OS: Ubuntu 20.04.6 LTS aarch64
Host: Raspberry Pi 4 Model B Rev 1.1
Kernel: 5.4.0-1082-raspi