If you use the Firefox web browser, you may occasionally encounter the PR_END_OF_FILE_ERROR that prevents you from accessing library databases. This error is Firefox-specific, and you should be able to connect to the databases using other web browsers such as Chrome, Edge, or Safari.
You can also attempt to resolve the error in Firefox by following one of the steps:
1) temporarily disable any third-party security software (such as BitDefender) to see if that helps
2) refresh your Firefox browser