I have installed our managed package in our client's Sandbox org. When I tried to open the Configuration page which is added on the tab of the package, I am getting below error message.
The value of the "" parameter contains a character that is not allowed or the value exceeds the maximum allowed length. Remove the character from the parameter value or reduce the value length and resubmit. If the error still persists, report it to our Customer Support team. Provide the URL of the page you were requesting as well as any other related information.
The same app same version is installed in my developer edition org which is working fine. I am able to open the tab over there and there is no error on the page as well.
EDIT
This is the page URL https://customdomain--packagename.visualforce.com/apex/vfpagename?sfdc.tabName=01rO0000000Abts