Try using the default container that comes with dnn upgrade

I have resolved a problem that is similar to this one... The issue is with the StartDate and EndDate columns within the database causing some sort of problem with DNN 6, this problem does not exist with DNN 5.6.3.

If you want to go ahead and resolve the problem, you should get rid of the StartDate and EndDate paramaters for the module that is causing this issue by doing the following:

- You MUST have access to your database, You need to run these queries within MSSQL Management Studio.

A- Find the ModuleID

SELECT * FROM ModuleS WHERE StartDate LIKE '%9999%';

Since the the problem was caused by System.ArgumentOutOfRangeException: Value of '12/31/9999 12:00:00 AM' is not valid for 'SelectedDate'. 'SelectedDate' should be between 'MinDate' and 'MaxDate'. I have placed 9999 for the LIKE statement. If your error was 2011, for example, you should replace it with '%2011%'.

B- Keep the moduleID in mind on the resulting query, if the moduleID was 100, you'd run this query next (Replace 100 with the ModuleID you've received from the previous query):

UPDATE Modules SET StartDate=NULL WHERE ModuleID=100;
GO
UPDATE Modules SET EndDate=NULL WHERE ModuleID=100;
GO

After this, you will need to recycle the application pool for your site, once done, try to refresh the page you are on and editing the HTML Module or whatever module that caused the issue.

I have tried your proposed solution by using Microsoft SQL Management Studio Express, but with varying success.
First, I reverted the update back to DNN 5.6.3, and set EndDate to 2014.

When I try your solutions, the following happens:

1. Reset EndData "9999" to "NULL" went fine in 3th parts module.
2. Reset to "NULL" in default DNN HTML module did not work, but the database value was written to 12/31/9999 - again.

I ran the same script in DNN "host / SQL" with the same result.