I updated my xslts using the package and then upgraded umbraco 4.0.3 to 4.5.2 and planning to do upgrade till version 6.x. The upgrade completed fine but my xslts are not working. An exmaple of the xslt is below

XSLT before upgrade 

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE xsl:stylesheet [
    <!ENTITY nbsp "&#x00A0;">
]>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxml="urn:schemas-microsoft-com:xslt" xmlns:umbraco.library="urn:umbraco.library" xmlns:Exslt.ExsltCommon="urn:Exslt.ExsltCommon" xmlns:Exslt.ExsltDatesAndTimes="urn:Exslt.ExsltDatesAndTimes" xmlns:Exslt.ExsltMath="urn:Exslt.ExsltMath" xmlns:Exslt.ExsltRegularExpressions="urn:Exslt.ExsltRegularExpressions" xmlns:Exslt.ExsltStrings="urn:Exslt.ExsltStrings" xmlns:Exslt.ExsltSets="urn:Exslt.ExsltSets" exclude-result-prefixes="msxml umbraco.library Exslt.ExsltCommon Exslt.ExsltDatesAndTimes Exslt.ExsltMath Exslt.ExsltRegularExpressions Exslt.ExsltStrings Exslt.ExsltSets ">
    <xsl:output method="xml" omit-xml-declaration="yes"/>
    <xsl:param name="currentPage"/>
    <xsl:template match="/">
        <xsl:variable name="imageFolder" select="/macro/imageFolder"/>
        <xsl:variable name="imageFolderContents" select="umbraco.library:GetMedia($imageFolder/node/@id, 'true')"/>
        <div style="clear:both; " class="slideshow">
            <xsl:for-each select="$imageFolderContents/node [@nodeTypeAlias='Image']">
                <xsl:if test="string(current()/data [@alias='umbracoFile']) != ''">
                    <a href="http://www.marhall.com/booking.aspx">
                        <img alt="{current()/@nodeName}">
                            <xsl:attribute name="src"><xsl:value-of select="current()/data [@alias='umbracoFile']"/><!--                 <xsl:value-of select="umbraco.library:UrlEncode(current()/data [@alias = 'umbracoFile'])" disable-output-escaping="yes" />--></xsl:attribute>
                        </img>
                    </a>
                </xsl:if>
            </xsl:for-each>
        </div>
    </xsl:template>
</xsl:stylesheet>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE xsl:stylesheet [
    <!ENTITY nbsp "&#x00A0;">
]>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxml="urn:schemas-microsoft-com:xslt" xmlns:umbraco.library="urn:umbraco.library" xmlns:Exslt.ExsltCommon="urn:Exslt.ExsltCommon" xmlns:Exslt.ExsltDatesAndTimes="urn:Exslt.ExsltDatesAndTimes" xmlns:Exslt.ExsltMath="urn:Exslt.ExsltMath" xmlns:Exslt.ExsltRegularExpressions="urn:Exslt.ExsltRegularExpressions" xmlns:Exslt.ExsltStrings="urn:Exslt.ExsltStrings" xmlns:Exslt.ExsltSets="urn:Exslt.ExsltSets" exclude-result-prefixes="msxml umbraco.library Exslt.ExsltCommon Exslt.ExsltDatesAndTimes Exslt.ExsltMath Exslt.ExsltRegularExpressions Exslt.ExsltStrings Exslt.ExsltSets ">
    <xsl:output method="xml" omit-xml-declaration="yes"/>
    <xsl:param name="currentPage"/>
    <xsl:template match="/">
        <xsl:variable name="imageFolder" select="/macro/imageFolder"/>
        <xsl:variable name="imageFolderContents" select="umbraco.library:GetMedia($imageFolder/node/@id, 'true')"/>
        <div style="clear:both; " class="slideshow">
            <xsl:for-each select="$imageFolderContents/Image">
                <xsl:variable name="filePath" select="umbracoFile"/>
                <xsl:if test="normalize-space($filePath)">
                    <a href="http://www.marhall.com/booking.aspx">
                        <!-- Change the link if this is a specific file -->
                        <xsl:if test="$filePath = '/media/42595/marhall_spadayhpbanner_jul131 (4).jpg'">
                            <xsl:attribute name="href">http://gifts.skchase.com/marhall/summerspa/</xsl:attribute>;
                        </xsl:if>
                        <img src="{$filePath}" alt="{current()/@nodeName}"/>
                    </a>
                </xsl:if>
            </xsl:for-each>
        </div>
    </xsl:template>
</xsl:stylesheet>

I have spent lots of time on it and would appreciate any help

I guess the issue is lying on this line $imageFolderContents/Image   this is always empty.