Instructions are old way. This was a solution, nothing current yet. Try: Clear the cookies ('problematic' site(s) only): Firefox > Preferences > Privacy > Cookies: "Show Cookies" Clear the cache: Firefox > Preferences > Advanced > Network > Cache: "Clear Cache Now"

Can prob follow this : https://knowledgebase.constantcontact.com/articles/KnowledgeBase/6894-error-request-entity-too-large

Please let us know if this solved your issue or if need further assistance.

Note that this is usually an issue with corrupted cookies that are send to the server as part of the HTTP request headers.

You can clear the cookies from the website.

You can inspect cookies and passwords and permissions for the domain in the currently selected tab via these steps:

• click the Control Center 'i' icon at the left end of the location/address bar
• click the arrow to expand the security message
• click "More Information" to open "Tools -> Page Info"
• click "Security" to inspect and modify cookies and passwords in a standalone window

If clearing cookies didn't help then It is possible that the cookies.sqlite file in the Firefox profile folder that stores the cookies got corrupted.

• rename/remove cookies.sqlite (cookies.sqlite.old) and if present delete cookies.sqlite-shm and cookies.sqlite-wal in the Firefox profile folder in case cookies.sqlite got corrupted.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox