Your changes could not be saved because this SharePoint Web site has exceeded the storage quota limit. You must save your work to another location. Contact your administrator to change the quota limits for the Web site.

Error Messages:
Your changes could not be saved because this SharePoint Web site has exceeded the storage quota limit. You must save your work to another location. Contact your administrator to change the quota limits for the Web site.

You see the below error when you try to upload the Files to a Document Library.

You see the below error while trying to drag files in the Folder opening the Library with Windows Explorer.

"Error 0x8007050F: The requested file Operation failed because the storage quota was exceeded.

To free up disk space, move files to a different location or delete unnecessary files. For more information, contact your system administrator."

You see the below error message while working with Workflows.

Solution:

Run this query on all the content databases : get the site which has the Quota limit set.

SELECT s.DiskUsed, s.DiskQuota, w.FullUrl from webs w join Sites s on w.SiteId = s.Id where s.DiskUsed > (s.DiskQuota * 0.9) and DiskQuota != 0

Make a note of the output of the above query. 

Run the following command and make sure what is the quota limit on the site collections on individual web applications and check the Quota Size:

Stsadm -o enumsites  -url

Run the below command to update the quota.

stsadm -o updatequota
 -quotaname <quotaTemplateName> [-contentdb <database name>]     [-nologfile][-quiet]

stsadm –o updatequota –contentdb WSS_Content

In my case, we don't have Quota Template and any Quota already set. I think the default Quota Limit came into picture and caused the error.

It also showed error message when i ran the above command. But looks like the limit was set to "0".

I was able to upload files directly and using Windows Explorer.

http://spmysitequota.codeplex.com/

You can use the above tool to updates Site Quotas using Quota Template.