.css and .js files only loading when refreshing page after deploy

Question

Whenever I'm deploying updates on our Magento 2 live environment, I run into the issue that on first page load, the .min.css files and sometimes the .js/.min.js files aren't loading (the browser runs into a 404 when trying to load the files from the server).

However, this only seems to be the case on first load after the deploy. When I then refresh the page, it suddenly finds the requested files (sometimes immediately on first retry, sometimes it takes a few attempts).

Does anyone have an idea why and how to fix this? I've tried to think of potential causes, but I'm already running cache:clean and cache:flush and the static signature should be a different one after the deploy.

To summarize some information that may be helpful:

• The servers are running in production mode, I am developing on a dedicated development server and pushing updates with git.
• The command used is setup:static-content:deploy -f
• Our company is using two servers and a load balancer to host the site
• Each server is being deployed individually
• The static files are signed (using a part of the git commit hash so both servers have the same signature)
• It affects both frontend and admin panel

---

EDIT

Here's the cache configuration in case this is relevant. Each server runs the static files in its own respective folder; this was changed from a shared static folder recently.

'cache' => [
 'frontend' => [
 'default' => [
 'id_prefix' => 'b1c_',
 'backend' => 'Magento\\Framework\\Cache\\Backend\\Redis',
 'backend_options' => [
 'server' => '<SERVER>',
 'database' => '1',
 'port' => '<PORT>',
 'compress_data' => '1',
 'compression_lib' => ''
 ]
 ],
 'page_cache' => [
 'id_prefix' => 'b1c_'
 ]
 ],
 'allow_parallel_generation' => false,
 'graphql' => [
 'id_salt' => '<SALT>'
 ]
],
'cache_types' => [
 'config' => 1,
 'layout' => 1,
 'block_html' => 1,
 'collections' => 1,
 'reflection' => 1,
 'db_ddl' => 1,
 'compiled_config' => 1,
 'eav' => 1,
 'customer_notification' => 1,
 'config_integration' => 1,
 'config_integration_api' => 1,
 'full_page' => 0,
 'config_webservice' => 1,
 'translate' => 1,
 'vertex' => 1,
 'amasty_shopby' => 1,
 'ktype' => 1
],

• Clong: varnish cache may be ? Sometimes we have to restart php on the server post deploy to make all the statics alive because if not they keep tagging the old release version
• Pascal F: @Claims we're not using varnish (yet), but redis - and full page cache is disabled in general. We recently switched from a shared static contents folder to two individual ones for the servers, not sure if something in redis would have to be reconfigured for that?

Answer 1

Some production servers use cloudflare for loading Js and Css files. after setup:upgrade command you need to refresh your cloudflare cache to save new created css and js files in cloudflare.

• Pascal F: We're using AWS as hosting provider, without cloudflare as far as I am aware