Some non-librenms sites suggest deleting anything in bootstrap/cache. I renamed them and tried again. Now Validate shows this:
In ProviderRepository.php line 208:
Class 'Fideloper\Proxy\TrustedProxyServiceProvider' not found
PHP Fatal error: Uncaught ErrorException: Undefined index: openssl_ver in /opt/librenms/validate.php:167
Stack trace:
#0 /opt/librenms/validate.php(167): Illuminate\Foundation\Bootstrap\HandleExceptions->handleError(8, 'Undefined index...', '/opt/librenms/v...', 167, Array)
#1 /opt/librenms/validate.php(84): print_header(Array)
#2 [internal function]: {closure}()
#3 {main}
thrown in /opt/librenms/validate.php on line 167