Sql-server – Will Installation of Service Pack 3 on SQL Server 2012 Web Edition (existing production) require database restore activity

I can reproduce this but I think you have a few options:

• not worry too much about full-text index bloat. Not many people are going to be searching for 'rtf1', 'pard' or 'wmetafile0' and I don't think it will affect your performance that much. You might get the odd clash if someone is searching for 'red' or 'blue' but I'd say this is fairly low risk.
• Clean the string up eg with RegEx I copied from here. Seemed to make a good go of it. Store it in a separate table with the stream_id ( which is the unique id for the document ) and full-text index that table instead:

-- Convert rtf to plain text
SELECT 
    CAST( file_stream AS VARCHAR(MAX) ) original
    , MDS.mdq.RegExReplace( 
        CAST( file_stream AS VARCHAR(MAX) ), 
        '\{\*?\\[^{}]+}|[{}]|\\\n?[A-Za-z]+\n?(?:-?\d+)?[ ]?', '', 1 )
FROM dbo.Documents

• Similar approach with a CLR function I adapted from here:

using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using System.Text;
using System.Linq;  // for TakeWhile

public partial class UserDefinedFunctions
{
    [Microsoft.SqlServer.Server.SqlFunction]
    public static SqlChars rtfToText( SqlChars inputRtf )
    {
        // RTF function lifted from here and adapted for SQL CLR:
        // https://stackoverflow.com/questions/23277178/richtextbox-throws-outofmemory-on-azure

        bool slash = false; //indicates if backslash followed by the space
        bool figure_opened = false; //indicates if opening figure brace followed by the space
        bool figure_closed = false; //indicates if closing brace followed by the space
        bool first_space = false; //the else spaces are in plain text and must be included to the result

        if (inputRtf.Length < 4) return new SqlChars ( string.Empty );

        int i = 0;
        i = inputRtf.ToString().IndexOf("\\pard");
        if (i < 1) return new SqlChars(string.Empty);

        var builder = new StringBuilder();
        for (int j = i; j < inputRtf.Length - 1; j++)
        {
            char ch = inputRtf[j];
            char nextCh = inputRtf[j + 1];

            if (ch == '\\' && nextCh == 'p') // appends \n if \pard, except for first
            {
                if (j > i && j < inputRtf.Length - 4)
                {
                    string fiveChars = inputRtf.ToString().Substring(j, 5);
                    if (fiveChars.Equals("\\pard"))
                    {
                        builder.Append("\n");
                    }
                }
            }

            if (ch == '\\' && nextCh == 'u') // to deal correctly with special characters
            {
                string fourChars = inputRtf.ToString().Substring(j + 2, 4);
                string digits = new string(fourChars.TakeWhile(char.IsDigit).ToArray());
                char specialChar = (char)int.Parse(digits);
                builder.Append(specialChar);
                j += digits.Length + 5;
                continue;
            }

            if (ch == '\\' && nextCh == '{') // if the text contains symbol '{'
            {
                slash = false;
                figure_opened = false;
                figure_closed = false;
                first_space = false;
                builder.Append('{');
                j++;
                continue;
            }
            else if (ch == '\\' && nextCh == '}') // if the text contains symbol '}'
            {
                slash = false;
                figure_opened = false;
                figure_closed = false;
                first_space = false;
                builder.Append('}');
                j++;
                continue;
            }
            else if (ch == '\\' && nextCh == '\\') // if the text contains symbol '\'
            {
                slash = false;
                figure_opened = false;
                figure_closed = false;
                first_space = false;
                builder.Append('\\');
                j++;
                continue;
            }
            else if (ch == '\\') // we are looking at the backslash
            {
                first_space = true;
                slash = true;
            }
            else if (ch == '{')
            {
                first_space = true;
                figure_opened = true;
            }
            else if (ch == '}')
            {
                first_space = true;
                figure_closed = true;
            }
            else if (ch == ' ')
            {
                slash = false;
                figure_opened = false;
                figure_closed = false;
            }

            if (!slash && !figure_opened && !figure_closed)
            {
                if (!first_space)
                {
                    builder.Append(ch);
                }
                else
                {
                    first_space = false;
                }
            }
        }

        // Return
        return new SqlChars(builder.ToString());
    }
};

I'm sure this isn't the world's most efficient CLR function but it did an ok job on some 100 documents I tested, with a few fails.

Let us know if you hear anything back on the connect item.

Without discounting anything stated in @Shanky's answer, it should be noted that the specific AppDomain being unloaded is in the [mssqlsystemresource] database. This is an internal database that stored built-in SQL Server functionality. Other built-in functionality resides in the [master] database. Even with the server-level configuration option of "CLR Enabled" turned off, you can still see one or both of these AppDomains being loaded if you use any of the following (and there could be other internal uses of CLR that are not in this list):

• Datatypes:
  • HierarchyID
  • Geography
  • Geometry
• Functions:
  • FORMAT
  • TRY_CONVERT
  • TRY_PARSE
• Features:
  • Change Data Capture
  • Dynamic Management Framework
  • Replication
  • Policy-Based Management

Run the following:

SELECT * FROM sys.dm_clr_appdomains;
SELECT * FROM sys.dm_clr_loaded_assemblies;

If no rows returned, then run the following:

SELECT FORMAT(GETDATE(), 'dd');
SELECT * FROM sys.dm_clr_appdomains;
SELECT * FROM sys.dm_clr_loaded_assemblies;

And you should now see an entry for "master.sys[runtime].xx" (where the xx is some number), but still no loaded assemblies. Now run:

DECLARE @Test [HierarchyID];
SET @Test = '/1/';
SELECT * FROM sys.dm_clr_appdomains;
SELECT * FROM sys.dm_clr_loaded_assemblies;

And you should now see a loaded assembly as well. It should be assembly_id 1 and that is the same entry in all databases: Microsoft.SqlServer.Types. This assembly shows up in all databases if you run SELECT * FROM sys.assemblies;, but it only truly lives in [master].