I recently have an incident with the same timeout error mentioned in the blog in below that customer would like to run report exceeding 4 minutes in EP. The same steps are used to extend the AsyncPostBackTimeout attribute except that AxScriptManager is searched/modified instead of ScriptManager in the master page mentioned in the blog.
We then encounter the “Code Block are not allowed in this file” error that following the blog in below does not resolve the error.
If you encounter similar error, here is another approach to extend AsyncPostBackTimeout
1) Open the master page from \Web\Web Files\Static Files\defaultaxV4 in the AOT
2) Search for the OnLoad() method to replace in something in below.
protected override void OnLoad(EventArgs e)
AxScriptManager scripts = AxScriptManager.GetCurrent(this.Page);
if (scripts != null)
scripts.AsyncPostBackTimeout = 600; // 600 seconds
//Call Header.DataBind to generate dynamics styles in header
3) Save and deploy the defaultaxV4 master page (Right click and select Deploy Element)