I was working on Sitecore upgrade from 6.3 to 7.2, then I reached Sitecore 7.0 rev.130424.
The upgrade process was completed successfully, but I found an issue while I was trying to open the "Index Manager" dialog in Sitecore 7.0 rev.130424.
The Sitecore upgrade documentation requires you to rebuild the indexes once you have done from 7.0 upgrade.
"The ContentSearch indexes must be built before you can take advantage of the Item Buckets and search features. This is done via the following wizard: Sitecore » Control Panel » Indexing » Index Manager."
That was the reason where I caught the dialog issue.
In fact, the index dialog is not the only dialog that did not work.
I checked Sitecore logs, but I didn't find any errors there. I checked the browser console, then I found that there is an error logged there, like the following:
Uncaught ReferenceError: showModalDialog is not defined
After searching about this issue, I found that Google Chrome disabled the API showModalDialog, as they announced the following:
showModalDialog is a bad API that we deprecated earlier this year, and in Chrome 37 we will disable support for it by default.showModalDialog was first introduced in Internet Explorer 4 and although it was never formally standardized, over time most other browsers added support for it. It allows applications to show a dialog of HTML content that freezes all other content while showing. showModalDialog is not a commonly used API: based on our usage counters, less than 0.006% of pages use it.
For reference, check the following link:
Sitecore provides two different solutions for this issue:
1- Upgrade your solution to Sitecore CMS 7.1
2- Install a patch for this issue.
If you want to stay with Sitecore 7.0, Then you have to install the following patch from Sitecore, and everything will work correctly.