NCBI staff occasionally perform site maintenance that requires taking NCBI Submission Portal or one of its components offline. We schedule such outages in advance and post announcements ahead of the work that usually lasts a few hours.  

If you continue seeing ‘unavailable’ messages for multiple days following the maintenance, your browser may be sending you to an old page. In technical terms, your Domain Name Service (DNS) resolving server has stored ("cached") an old value for the www.ncbi.nlm.nih.gov site. 

Try these ways to fix the problem: 

• Clear your browser’s cache and close and restart the browser. 
• Use a different browser (see the Browser Advice for NCBI Web Pages). 
• If you have bookmarked your starting page or saved it as favorite: 
  • Remove the bookmark. 
  • Copy and paste in your browser the NCBI Submission Portal home page URL (web address): https://submit.ncbi.nlm.nih.gov/ 
  • From there, navigate to the component of the Submission Portal that you need. 

If the problem continues, you may have a DNS problem that needs to be fixed. If you are accessing NCBI from within an institution, contact your internet technology (IT) specialist for help.