Access denied or empty body

Start by reproducing the 403 or empty-body response with the shown prerender-node middleware, comparing requests with and without the Googlebot user agent. Inspect the beforeRender and afterRender hooks, Redis cache behavior, and the /render?url=https://www.google.com/ path. Done means identifying the failure and restoring a non-empty response with useful error logging.

Issue: HTTP ERROR 403 - Access denied.
Issue appears during last 3 days, before everything was working fine.

Setup:

• Server is Linux Ubuntu
• Local prerender under Node, which is working fine, can access page: /render?url=https://www.google.com/
• "prerender-node" setup with Redias cache.
• Assessing website by browsing with googlebot in User agent string.

Deep dive into testing:

• Website is accessible without googlebot in User agent string.
• In afterRender event getting empty body for any request url
• In afterRender error object is null
• Redis cache is working, even when removing cache mechanism fully, issue persist
• Files permission is correct and was not changed.
• When removing app.use(prerender); website again accessible with googlebot in User agent string.
• Version of packages including "prerender-node" was not released, so nothing to update
• Version of "google-chrome-stable" checked and updated to latest one - 92.0.4515
• Reason of this all points is not applicable: [https://docs.prerender.io/article/25-empty-or-partially-rendered-pages](Empty or partially rendered pages) as it is working with url /render?url=https://www.google.com/
• pageDoneCheckInterval increased up to 20sec to make sure it is not a reason
• Getting empty body immediately, some some error is happening there, but no any error log, as I have pageDoneCheckInterval: 5000, I should get response in 5 sec, which is not happening.

Ideas what can be a reason:

• Something got broken in process of Prerender in some dependencies.
• There is some limit of requested pages per month, but as I use Prerender locally, as I understood it is not limited somehow.
• Some another crazy reason))

Code prerender section for any case:

// Setup prerender
prerender = require('prerender-node');
prerender.set('protocol', 'https');
prerender.crawlerUserAgents.push('Validator.nu/LV');
prerender.crawlerUserAgents.push('W3C-checklink');
app.use(prerender);

// Setup redis cache
var redis = require("redis"),
	client = redis.createClient();

client.flushdb( function (err, succeeded) {
});

prerender.set('beforeRender', function(req, done) {
	client.get(req.url, done);
}).set('afterRender', function(err, req, prerender_res) {
  if ( prerender_res ) {
    client.set(req.url, prerender_res.body)
  }
});

Anyway this was working previously very long and very stable.

Any idea will appreciated, thanks in advance.