I have a password in parameters in services.yaml, for example "xxx%xxxxx%xx" and when i want to do GetParameter it returns me only "xxxxx" and error 500
parameters:
api_passwd: "x%xxxxx%xxx"
First off, avoid using images in your questions. Just copy/paste the relevant portions of the error into your code.
Secondly it sort of looks like you are testing in production mode? You should have gotten a completely different error message. Make yourself a simple console command for testing these sorts of things.
In any event, Symfony treats % as a rather special character. In general, avoid using % in your yaml values. Never really noticed it myself which is why I am actually posting an answer. The workaround is to double up the % character. Basically escaping it.
parameters:
api_passwd: "x%%xxxxx%%xxx"
The extra % characters will be stripped out when you retrieve the value.