I encountered an error during the DOI installation process. Hope everyone help me. Thank you very much
Hi @Ngoc_Tuan_Nguyen Welcome to the PKP Community Forum! 
The error is more about the activation of the DOI. It is difficult for us to help you without more context.
What version of OJS are you using?
Have you completed the DOI Plugin configuration?
How do you do the DOI deposit from your OJS?
I’ll share this documentation with you in case it helps, https://docs.pkp.sfu.ca/doi-plugin/en/doi-plugin and https://docs.pkp.sfu.ca/crossref-ojs-manual/en/config#manual-deposits (it’s for OJS 3.2, but the process is similar for OJS 3.3)