How do I insert tabs in the log4net layout pattern?

This worked for me:

1) When your logging class is instantiated, add this line:

log4net.GlobalContext.Properties["tab"] = "\t";

2) Then in the log4net XML, make a reference to your newly-created log4net property. For example:

<conversionPattern value="%property{tab}%message%newline" />

You can type tab into pattern without escaping (see space between level and date):

<conversionPattern value="%level    %date{HH:mm:ss,fff} ..." />

I cant write tab in visual studio, because it writes spaces, but I typed tab into notepad++ copy it (ctrl+c ctrl+v) and it is working.

EDIT: stack overflow replaced my tab with spaces. So you need to type your own tab

Caveat: I haven't actually used log4net. But if I understand correctly, the configuration is an XML file, isn't it? And the pattern is just text with some special tokens. So have you tried embedding actual tab characters in your pattern? The XML sequence for a tab is 	, e.g.:

<conversionPattern value="%utcdate&#9;[%thread]&#9;%-5level&#9;%logger&#9;%message%newline" />

Or if you're supplying the pattern some other way (perhaps via the PatternString constructor or whatever), just include tab characters in the string you're passing in. The docs for that constructor defer to the PatternLayout docs to talk about the string itself, and there they say:

You are free to insert any literal text within the conversion pattern.

(Their emphasis.) Worth a try, anyway...