The NCBI web site supports the current release of Chrome, Firefox and Safari, and the previous two versions. It also supports IE11 and above, and the current release of Microsoft Edge. "Supports" means that NCBI will actively work to identify and fix bugs.
Due to the complexity of the modern Internet, digital traffic flow can be intermittently disrupted in a number of places. These transient disruptions may cause your browser to display and/or cache incomplete or corrupted pages. Clearing your browser's cache and history can fix these problems. Please see the relevant sections below for instructions on how to do this.
NCBI is using HTTP1.1 compression/content encoding for delivering data from the Entrez databases (e.g., PubMed). Data compression allows data to be sent faster and can result in significant performance improvements for users who have slower network connections.
Most recent versions of popular browsers are by default enabled to use HTTP1.1. If, however, you see the message, "Warning: Page has Expired," after using the back button in your browser, you should enable HTTP1.1 compression in your browser.
If, after enabling HTTP1.1 compression (be sure to close and re-launch the Browser), you still see the "Warning: Page has Expired" message, it is possible that another application is causing the warning to appear. For example, we have determined that Norton Internet Security (Symantec's firewall program), can cause the Browser to display the error message even with HTTP1.1 compression enabled if the firewall is configured to monitor HTTP connections (the default configuration).
If, you wish to disable HTTP monitoring in a firewall program, you should fully understand the consequences of doing so. We suggest that you either consult the product documentation or contact the vendor.
If you see a message that specifically mentions being "Blocked for Possible Abuse", please note that the "Access Denied" error message is not meant to imply any maliciousness on your part. Because of the prevalence of firewalls, a single IP address may represent many users, all of which will be affected if we block the firewall's IP address.
If this does occur, please send a message to firstname.lastname@example.org with the following information:
With this information, we will be able to unblock your system and, depending on the specifics of the case, can also offer advice about how to access our data in ways that will prevent future blocks.
For more information on your specific browser's cookies, please consult your browser's documentation. If you have problems using cookie-dependent features of PubMed even after enabling cookies, possible reasons may include:
Modern browsers store copies of viewed web pages in a cache so that, if requested again, these pages can be viewed more quickly. However, if a page does not load completely or correctly, your browser may store a corrupted version of the page that will be shown when you attempt to load the page again. Clearing a browser's cache will fix these problems, and should always be a first step when confronting page load errors. In some cases clearing a browser's history may also fix these problems.
Modern browsers also allow "private browsing", which prevents certain types of data flow and storage. Some stringent private browsing settings may disrupt data flows that the NCBI web site needs in order to function properly. If you cannot access NCBI web pages even after clearing your browser's cache and history, you may want to consider adjusting your browser's privacy settings.
To assist users who may not have a mouse, trackball or touch mechanism to control a browser's cursor, NCBI has enabled the use of AccessKeys for easier keyboard navigation of common links and page elements within the NCBI website.
Because each browser implements AccessKeys differently, we have also provided a list of Browser AccessKeys and actions.
Last updated: 2016-12-01T17:09:58-05:00