Please try these troubleshooting steps to see if you can get back into WorldShare:
First, clear your browser's cache and cookies. We often find that the web caching inside browsers can cause issues. Another way to troubleshoot is to open a private viewing session and try to log in to WorldShare without cookies set and cached browser memory.
If you are using a bookmark to access the page, the bookmark URL may be faulty. The WorldShare URL structure is https://[Your RegID].share.worldcat.org/wms
Turn off any extensions or ad blockers that you've added to your browser, then restart to see if it changes the behavior.
If this fails, try logging in on a different browser to see if it gives you the same error. That could point us to a browser issue outside of caching.
If you are still having issues in a new browser, please try on a different computer. It could be a setting on your computer or network that is blocking access.
If none of these steps work to clear the issue, contact OCLC Support.