"Check Readiness" button loops back to documentation on Check Your Lightning Experience Readiness
Availability of Checks and Reports
Admins who meet these requirements can run the Lightning Experience Readiness Check and the Lightning Experience Visualforce Check.
Both checks are available in sandbox and production environments and supported if you’re set to a Fully Supported Language in Salesforce. Reports are available in English only.
The checks are available for customers with certain IP address restrictions. Whitelist the following IP addresses for users who run Readiness Check and Visualforce Check.
Look into below article.
Hi Rajesh -
These are just IP addresses - not IP Ranges. The set up seems to explicitly be looking for a range.
How do you define the range?
- From Setup, enter Network Access in the Quick Find box, then select Network Access.
- Click New.
- Enter a valid IP address in the Start IP Address field and a higher IP address in the End IP Address field.
- The start and end addresses define the range of allowable IP addresses from which users can log in, including the start and end values. If you want to allow logins from a single IP address, enter the same address in both fields.
- The start and end IP addresses must be in an IPv4 range and include no more than 33,554,432 addresses (225, a /7 CIDR block).
Sorry. I'm out of options. If none of the above helped. I would suggest raise a case with salesforce.
From what I understand from Support, there is a "fix" in the works. That's great. But the issue for us, as it is often, is lost time. We needed an answer when I initially tried to run the assessment a week ago.
Hope that makes sense as to why it would work in one environment and not the other! Thanks Nicole.
Here is an article to guide those who may have similar concerns: