All children were disabled due to too many connecton errors in SMTP

[shiv2587]

I tried both the wordlist and the single password methods but same error everytime. Here i provided the actual key but still it shows 0 valid password found and in the wordlist i've also provided the actual key but shows the same error. Also tried the GUI one but same error.
hydra -s 25 -l useraddress -p password -t 1 smtp.gmail.com smtp
Hydra v9.4 (c) 2022 by van Hauser/THC & David Maciejak - Please do not use in military or secret service organizations, or for illegal purposes (this is non-binding, these *** ignore laws and ethics anyway).

Hydra (https://github.com/vanhauser-thc/thc-hydra) starting at 2023-08-25 23:12:15
[INFO] several providers have implemented cracking protection, check with a small wordlist first - and stay legal!
[WARNING] Google Mail and others have bruteforce and hydra detection and send false positives. You are not doing anything illegal right?!
[WARNING] !read the above!
[DATA] max 1 task per 1 server, overall 1 task, 1 login try (l:1/p:1), ~1 try per task
[DATA] attacking smtp://smtp.gmail.com:25/
[STATUS] 2.00 tries/min, 2 tries in 00:01h, 1 to do in 00:01h, 1 active
[ERROR] all children were disabled due too many connection errors
0 of 1 target completed, 0 valid password found
Hydra (https://github.com/vanhauser-thc/thc-hydra) finished at 2023-08-25 23:13:57

[Tr4cer0]

If necessary, you may need to confirm whether you can connect to the server or attach the relevant pcap packet capture results so that the issue can be analyzed.

[xmehulx]

Setting up trusted SMTP server and running the mentioned commands does not result in any issue. And as your output also mentions, there will be false positives sent back. Also, if you debug your command with -d you'll see the passwords are actually being attempted but not given back any confirmation. So it could really be due to server settings sending back false positives to you and hydra_heads in soruce code all failing, before throwing the provided error.