Hi @kovacs.szilard90, there is a similar error in this case installing the ffi gem: https://community.bitnami.com/t/unable-to-migrate-database-when-upgrading-redmine-to-3-6-4-2/61074/28
It is fixed by installing necessary build tools:
sudo apt-get install build-essential
Does it work for you now? If not, could you explain what you were doing when this error occurred?
Also, if it did not resolve your question, we have a Support Tool that will gather relevant information for us to debug the issue. Could you please download and execute it on the machine where the stack is running by following the steps described in the guide below? You must click on the platform or cloud that you are using to find the correct instructions.
How to Run the Bitnami Support Tool
Please note that you need to paste the code outputted by the tool in your reply.