/NLog/LayoutRenderers/VariableLayoutRenderer.cs
InternalLogger.Warn("${{var={0}}} should be declared as <variable name=\"var_{0}\" value=\"...\" /> and used like this ${var_{{0}}}. Because of unsafe Layout={1}", Name, layout);
must be
${{var_{{0}}}}
Thank you for reporting. Have created #3191
Thanks @lobster2012-user! This will be fixed in NLog 4.6.1 馃憤
Most helpful comment
Thank you for reporting. Have created #3191