Many Confluence pre 4.x users have User Macro that contain wiki markup which will not work when their Confluence are upgrade to 4.x and above. Please follow the steps below to convert those user macro:

1. Ensure that you are login to Confluence as a member of confluence-adminsitrators
2. Install Confluence Source Editor
3. Create a new page

4. Choose "Insert Wiki Markup" macro and copy paste your macro content. For example:

   {section}
     {column:width=300px}
       {panel}
         *Details:*
         {toc:maxLevel=3}
       {panel}
     {column}
   {section}

5. Click Tools and choose View Storage Format. The following string will be provided: 

   <ac:macro ac:name="section">
     <ac:rich-text-body>
       <ac:macro ac:name="column">
         <ac:parameter ac:name="width">300px</ac:parameter>
         <ac:rich-text-body>
           <ac:macro ac:name="panel">
             <ac:rich-text-body>
               <p>
                 <strong>Details:</strong>
               </p>
               <ac:macro ac:name="toc">
                 <ac:parameter ac:name="maxLevel">3</ac:parameter>
               </ac:macro>
             </ac:rich-text-body>
           </ac:macro>
         </ac:rich-text-body>
       </ac:macro>
     </ac:rich-text-body>
   </ac:macro>

6. Paste it into your user macro to replace the wiki markup
7. Discard the previously created page
8. Save the user macro

Source : On converting wiki markup based user macros for use with Confluence 4 by David Simpson