When moving a Drupal 8 site from one server to another sometimes a frustrating error message may appear after you upload the database and try out the new location. The error tells you there was a problem and you need to try back later. This may be a “sync” error. If you have drush installed properly you can run the “drush cr” command and that should clear the cache and put you in sync. But if drush does not work or if it isn’t installed — or whatever — then you might try using your browser to crank up phpMyAdmin and run some sql commands. These are the commands I run and have been successful:

TRUNCATE cache_config;
TRUNCATE cache_container;
TRUNCATE cache_data;
TRUNCATE cache_default;
TRUNCATE cache_discovery;
TRUNCATE cache_dynamic_page_cache;
TRUNCATE cache_entity;
TRUNCATE cache_menu;
TRUNCATE cache_render;
TRUNCATE cache_toolbar;

No guarantees, but it may be worth a shot.