but how come that the curl Create Invoice API call works just fine?
curl -X POST https://lnbits.mydomain.tld/api/v1/payments -d '{"out": false, "amount": 1000, "memo":"testtest"}' -H "X-Api-Key: <my_invoice_key>" -H "Content-type: application/json"
0 sats \ 1 reply \ @ek 16 Aug
Does this error happen consistently with SN?
failed to create test invoice: Unable to connect to http://lnbits-phoenixd-phoenixd-1:9740
Afaict, we tried the domain you provided us (lnbits.mydomain.tld) but LNbits returned this error. Maybe it wasn't able to reach the container when it tried but it would work on retries?
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The container must have reachable as it is running next to the Lnbits container, and I tried the curl command literally a few secs later, successfully.

That said, I went through the process again just now - and it magically works now. I can save the incoice key, without error message. Weird. but at least it works
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Can you try specifying the amount in msats?
curl -X POST https://lnbits.mydomain.tld/api/v1/payments -d '{"out": false, "amount": 1000, "unit": "msat", "memo":"testtest"}' -H "X-Api-Key: <my_invoice_key>" -H "Content-type: application/json"
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It does work in the sense that it returns a proper BOLT11 invoice, But LNBits seems to convert msat -> sat incorrectly. 10000msat becomes a 100sat invoice amount (should be 10sats).
It's still not an explanation for the OP error message
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It appears that msat is not a valid unit for LNBits, but instead of throwing an error, they just divide amount by 100.
I raised this issue: https://github.com/lnbits/lnbits/issues/2642 Let's see what they respond.
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In the meantime we stopped using msats for lnbits if you want to give it a shot.
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