DE country almost always return MS_MAX_CONCURRENT_REQ

I know the error is not caused by this gem, but how we can handle this? VIES global limit for Germany is a joke, wondering if there's an alternative provider we can connect to?

[yolk]

I am not aware of any alternative provider, and it IMO wouldn't make sense to offload/cache the data elsewhere; because the only authority in this regard are the official – and yes somewhat awkwardly limited – german servers.

So the only way to handle this is to simply keep retrying the request.

[momolog]

So the only way to handle this is to simply keep retrying the request.

@yolk What would be the best way to do that when using valvat with Rails, i.e. like

  validates :vat_number, valvat: { lookup: true }

?
Is there a config option that retries the lookup after 5 seconds? Or can the validation be made pass when the rate limit is hit (I know, not good, but what is the alternative?).

[yolk]

Moin @momolog,

the default behavior of the rails integration (and your code snippet) should validate to true if the web service is down (see the docs you mentioned). Does it behave differently in your case?

But I wouldn't recommend handling it this way. Instead I would store an new VAT-Number in the DB marked as :not_verified, and start validation it in a background job and mark it as :verified or :invalid when the web service is reachable. Valvat::Lookup.validate(record.vat_number) returns nil if the web service is down; so I would keep retrying it till you get an definitive answer back.

It is out of the scope of this gem to handle the background processing, sorry!

[momolog]

Does it behave differently in your case?

No, it doesn't, you are right, I had overlooked that, thanks.

But I wouldn't recommend handling it this way. Instead I would store an new VAT-Number in the DB marked as :not_verified, and start validation it in a background job and mark it as :verified or :invalid when the web service is reachable. Valvat::Lookup.validate(record.vat_number) returns nil if the web service is down; so I would keep retrying it till you get an definitive answer back.

Makes sense, thanks for the explanation.

It is out of the scope of this gem to handle the background processing, sorry!

Absolutely. Cheers!

[vatfix]

DE’s VIES servers are notorious for hitting MS_MAX_CONCURRENT_REQ even at low volumes.

My workaround:

• Detect the rate-limit error specifically.
• Queue the retry for later (even a short 10–30 sec delay helps).
• Cache successful validations for a few days so you don’t re-hit the same VATs.

I log all failed attempts and retry them asynchronously until I get a definitive result. This avoids blocking the main process while still ensuring everything eventually gets validated.