Site errors

I noticed that my site began to work with errors. I don't know how to find and fix them. What resource can help solve the problem? Are there such free resources?

Many resources are paid for finding site errors. I can suggest one site where there are free and paid options. This website error checker https://pr-cy.io/ You can try the free features. You will be able to find website errors. The site also gives recommendations on how to remove them. You must monitor the site regularly to eliminate errors.