Having Trouble using my Rails Application to Fly.io

I have deploy my Rails application on Fly.io with success, everithing work fine except one thing. when i recond one product i have this error on my error monioring

ArgumentError: key must be 32 bytes

happend on this file (Gem)

[GEM_ROOT]/gems/activesupport-7.0.4/lib/active_support/message_encryptor.rb:172:in `key='
cipher = new_cipher
cipher.encrypt
cipher.key = @secret

Everithing work fine on local, but on Fly.io i have this error.
Please, i don’t know what happend

thanks

Using Ruby “3.1.2” and Rails 7.0.4

It looks like your RAILS_MASTER_KEY is not set correctly. This key is typically in config/master.key, but may be in config/credentials/production.key.

That value should be 32 hexadecimal characters. Run the following command:

fly secrets set RAILS_MASTER_KEY=61f544e7e5560326b7d0933e71c9ad08

… replacing the 32 hex characters in the line above with the value from your master key.