What does Chrome console say?
Have you tried with vanilla Xcillion? That way you can rule out any theme issues.

Hi, Tycho

Thanks a lot for your answer.

It seems that there is a: Uncaught Sys.WebForms.PageRequestManagerServerErrorException: Sys.WebForms.PageRequestManagerServerErrorException:

at: Error.create (DOMAIN/ScriptResource.axd?d=qsKWPUfPuCDqfFnPqTBAPvzV5iwPLf3oyjVcjzAzsQc-cnDXkLXDyACNqAAJfyFewRfTSvPF-IOOyjBFVIOJU1bk2-_N0qKRmNrPMeyK7A62Z3fYf7JTrawuzVkeSu_Tc1ghYg2&t=ffffffffaa493ab8:5:2736)

Regarding the second question, I have already changed the Skin to Xcillion for the login page, using the SQL Server Management Studio, and the behavior remains the same.

Next step would be the IIS logs. Anything in there?

Well, there are entries with GET /ScriptResource.axd but the log files are rather big. Should I be looking for something specific? Or try to read those to the end, searching for anything unusual?

Since it fails to create ScriptResource.axd, I even tried to give full permissions for all users to the root directory, and then tried to login. Again, with no luck and I reset the permissions back.

Check your database size... It might be too large to log any events in your environment, and then cascades an error that causes an underlying JS exception on login.  Clearing out some database space and/or increasing the allowable growth size might fix this.  

If not, check the web browser developer tools to see what errors might be seen on the front end, and then check the log files for any other related errors.  (Also, in some instances, you might want to check the Windows Event Log to see if there are any additional suppressed exceptions that might be helpful.)  

Thank Will for your answer.

The Database is about 1,6 GB. The EventLog has 606,729 entries.

Should I run the commands:

1. TRUNCATE TABLE EventLog
2. TRUNCATE TABLE SiteLog

in order to reduce the size?

Thanks in advance for any help.

First, you need to verify the root cause before actually running any commands (that may do nothing or make things worse).  Look in your event logs to see what the errors are, in addition to the web browser developer console.  This will help you understand WHY the login isn't working before you fix the unknown issue. 

Video:  How to check your logs

Next, if the database size issue is verified in the event logs... 

You should be able to take a look at the database and/or control panel to determine how much disk space is being used.  

• How to determine the size of your database using T-SQL

Then, check your SQL Server settings to determine if the files are too large.  If you have a web host, then contact them or use their control panel to do the same thing.  

The cleanup steps you take really depend on the website, client, and any data retention policies that may or may not be in place (or exist by law).  

However, in the most general sense, you may want to run the following commands, after ensuring you have a VALID and FULL backup of your entire website (database and files).  (Oh, and I'd also recommend using App_Offline.htm or something to be sure no further issues or interruptions occur.)  

The following three queries can be run at the same time, but might take a while to finish, depending on the age/size of the website database.  As-is, this will delete any logs older than 90 days (in the database only).  

DELETE FROM [dbo].[EventLog]
WHERE [LogCreateDate] <= DATEADD(day, -90, GETDATE());

DELETE FROM [dbo].[SiteLog]
WHERE [DateTime] <= DATEADD(day, -90, GETDATE());

DELETE FROM [dbo].[ScheduleHistory]
WHERE [EndDate] <= DATEADD(day, -90, GETDATE());

Following a successful run of the three above queries, you can run the final one below to get the database back down to a manageable size.  

DBCC SHRINKDATABASE (N'REPLACE-WITH-YOUR-DATABASE-NAME');

This should not be done too often.  

Well, it seems that there is an issue with the Database size. Here is what I get reading the log files:

2023-03-01 06:11:33.755+02:00 [srvr02][D:13][T:71][ERROR] DotNetNuke.Services.Log.EventLog.DBLoggingProvider - System.Data.SqlClient.SqlException (0x80131904): Could not allocate space for object 'dbo.EventLog'.'PK_EventLogMaster' in database 'MYDB' because the 'PRIMARY' filegroup is full. Create disk space by deleting unneeded files, dropping objects in the filegroup, adding additional files to the filegroup, or setting autogrowth on for existing files in the filegroup.

One other thing is that the log files are huge and keep logging the same information above.

Although this is rather strange since this is the 4th largest database in this machine. I found out about this by executing:

EXEC sp_databases;