[Support Guide] Understanding and debugging prerendering

Our staff can flush the cache for you, but it is not likely we’ll see your request in a timely-enough fashion to do so. Unfortunately you didn’t include the URL here so I couldn’t “just do it” when I did happen to see this quickly…

Hello @fool,

It looks like Facebook does not use pre-rendered page.
When we try with Facebook Sharing Debugger it retrieves the default page instead of the pre-rendered version with the meta tags. Pre-render page works for all other crawlers I tested. We are within the limit of 1MB cut off facebook suggests.

By running curl to simulate the Facebook crawler we get the pre-rendered page. The real facebook crawler doesn’t.

Could you tell us a URL that shows this behavior, please?

Thanks for the fast response, here is a link you can test:

OK. We are definitely sending the prerendered content to facebook (you can test:

curl -v -A facebot https://share.100mentors.com

…returns different content than:

curl -v https://share.100mentors.com

So I guess you’ll need to work with Facebook to debug what’s happening if it doesn’t work like you’re expecting, and if you didn’t have any luck following the debug steps above (which will likely help you expose the problem)

The docs state the prerender is cached for 24-48 hours.

Does this happen for every deploy? Or does the cache only get updated once a day or every other day regardless of the latest deploy?

The cache is created on demand - we get a request for a prerendered page not already in cache, we attempt to prerender it and if successful, store it in that 24-48h cache (which is implemented something like: “is this asset in our prerender cache >24 hours old? Then, we will schedule it for removal sometime in the next 24 hours”.)

This cache is handled 100% independent of any deploy - whatever is live at the moment of the request is received & prerendered, it is cached for 24-48h regardless of how many times or changes you may deploy after that.

Hello and thanks for the reply.
We figured out what was happening.
Facebook was crawling the root page because og:url was set to our root page instead of the full url.
Other crawlers that worked probably don’t check the og:url.
Prerendering is working fine!