CLR Errors – Follow Up

A few weeks ago I posted about an issue I was having with CLR failing on one of my production servers. While a reboot fixed the problem it was a temporary fix and happened on a couple of further occasions. Still not being able to find the root cause Microsoft recommended a complete removal and reinstall of the .NET framework.

One of the Microsoft support team advised running the following query which loads CLR and then traverses through all the registered assemblies. This quickly shows up any problems with CLR and SQL Server integration even if the problem is not showing elsewhere.

1. select * from sys.assemblies

Seeing the following is not a good thing:

Msg 6512, Level 16, State 27, Line 1

Failed to initialize the Common Language Runtime (CLR) v2.0.50727 with HRESULT 0x80004005. You need to restart SQL Server to use CLR integration features.

Removing the .NET Frameworks

Firstly I downloaded the .NET Framework Cleanup Tool from http://blogs.msdn.com/b/astebner/archive/2008/08/28/8904493.aspx

With the tool installed on the server and all SQL services shut down and set to manual start I performed an uninstall of all of the .NET Frameworks in the order

• 3.5
• 3.0
• 2.0

The removal complete a server restart was in order. Once restarted it was time to

Reinstall the .NET Frameworks

Here’s the interesting thing, there’s actually no need to go through and reinstall each individual Framework, in fact just download and install .NET Framework 3.5 SP1 from Microsoft.

Once the install was complete and the server restarted I brought the SQL services back online (and reset their services to start automatically)

Checking sys.assemblies again gave me positive results

name      principal_id           assembly_id          clr_name               permission_set     permission_set_desc          is_visible                create_date                modify_date         is_user_defined

Microsoft.SqlServer.Types 4              1              microsoft.sqlserver.types, version=10.0.0.0, culture=neutral, publickeytoken=89845dcd8080cc91, processorarchitecture=msil          3              UNSAFE_ACCESS  1              2008-07-09 16:20:00.070                2008-07-09 16:20:00.413 0

Since the reinstall I’ve not experienced further issues. It’s a shame that Microsoft were unable to give me a root cause to the problem, however it’s great to have it resolved.

CLR Errors In Replication

Did you know that .NET components are used in replication? I sure didn't until I tried to add a new publication and perform a snapshot.

I had not troubles creating the publication or adding the subscribers but when I attempted to run the snapshot I got the following error:

Source: Replication
Exception Type: Microsoft.SqlServer.Replication.ReplicationAgentSqlException
Exception Message: Failed to initialize the Common Language Runtime (CLR) v2.0.50727 with HRESULT 0x800

Not a whole lot to go on there. There happens to be a DMV which will provide you with the status of CLR in SQL.

select * from sys.dm_clr_properties

I was expecting to see

name    value
-----------------------
directory    C:\WINDOWS\Microsoft.NET\Framework64\v2.0.50727\
version    v2.0.50727
state    CLR is initialized

but instead I saw

name    value
-----------------------
directory  
version   
state    CLR initialization permanently failed

Time to open a support case with Microsoft.

After running through some troubleshooting steps with the MS engineers, including verifying the .NET install was good (see http://blogs.msdn.com/b/astebner/archive/2008/10/13/8999004.aspx) the decision was ultimately made to restart SQL to see if this resolved the problem.

After the restart everything was running smoothly and there were no issues performing snapshots. Sadly the restart eliminated any chance of getting a root cause for the problem. I've got a filtered dump setup to try and capture something in the event that it happens again. I kind of hope that it does just so we can find out exactly what the cause was.

Here are a couple of interesting notes that I found from this:

• .NET Framework 3.5 is just a wrapper for .NET 2.0
• You can log all .NET events to disk (see http://blogs.msdn.com/b/junfeng/archive/2004/02/14/72912.aspx)
• In the event SQL encounters a .NET/CLR error then it will fail and set a flag internally. That flag will not be reset unless the SQL Instance is restarted and so any CLR functionality will fail
• You want to have your SQL Instance configured to write dumps to a drive with more free disk space than you have memory on your server. By default dumps will be written to the log directory. You can change this by opening "Error and Usage Settings" from the start menu, going to options and changing the error reporting location. Note, you have to restart SQL for this to take effect as this information is read in at startup

Update on Wednesday, September 29, 2010 at 9:14PM by Nic

I've posted a follow-up to this post with steps for the permanent resolution to the issue at http://englishtosql.squarespace.com/english-to-sql-blog/2010/9/29/clr-errors-follow-up.html