Tips to resolve SharePoint 2010 Ribbon stuck at “Loading…” issue

Recently, we have run into SharePoint 2010 Ribbon stuck at “Loading…” issue when we click Document tab for any document library as in the following screen shot. 

This issue seems to be common for many SharePoint environment and we are able to resolve this finally. Here are the steps you could follow to track down the root cause and fix it.  

1. First you should verify the some of the test cases and identify the scope of the issue.

a. Whether this in consistent for ALL sites on the physical server. If the answer is yes, this might be related to server configuration.

b. Whether other functions like "Site Actions" and "Add Documents" are working. If not, since these functions are related to javascripts, it might be the script issues.

2. Second you should verify "DisableLoopbackCheck" that could cause this issue. This is particular important if you are using SharePoint web service. See here for more information.

The loopback check functionality is stored in the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\DisableLoopbackCheck

3. Third is to check “Allow DNS Suffix Appending to Unqualified Multi-Label Name Queries”. This problem is actually caused by a new concept called DNS Devolution that Microsoft introduced in Windows 7 and Windows 2008 R2. Here is the procedure posted by Wilson Leung that could help.

Check Local Computer Policy > Computer Configuration > Administrative Templates > Network > DNS Client.  Enable “Allow DNS Suffix Appending to Unqualified Multi-Label Name Queries”.  Then flush the DNS by running a ipconfig /flushdns in command prompt.

4. The forth step you should check the permissions of the application pool account to the folder of the java scripts /_Layouts folder. You could verify other permissions on 14 hive folders. If the application pool account does not have permission to read the java script, it might cause such issue.

5. The final try before additional debugging is to if everything is fine at this point just like we had this time, you would need a developer to debug the java script and identify the breaking point. You could use either Web Developer on Firefox or IE developer tools. You could also use Fiddler to track the calls.

We are getting the following error when we debugging the code through Firefox Web Developer. 

SCRIPT1009: Expected '}'
core.js?rev=s7ZeJ4F%2Bz78dpGWvo%2FG%2BnA%3D%3D, line 2 character 238748

You should verify whether core.js has been corrupted and replace it with OoB one. If you are adding some customized java script, the toll will indicate whether it is and you should fix the java script.

At this time, you should be able to fix SharePoint 2010 Ribbon stuck at “Loading…” issue.