I have just purchased VisualMicro.
I am attempting to burn the bootloader to a Pololu A-Star atmega328PB 8MHz 3.3V.

I receive the following error:

Burning a new bootloader
This board does not support the burning of a bootloader
Burn failed 

When I try to Build an Arduino project, I get a Pop-Up "Error reading vartians paths".

Compiling 'READ_PAC_ID_328PB' for 'Pololu A-Star 328PB'
Build Folder: d_breadboard_avr_a-star328PB/Release"
Summary: Header=1 Prototypes=4 Imports=0
Additional Defines:
Api: 1.1811.24-0
Sketch Book: "file:///C:/Users/Robert/Documents/Arduino"
Sketch Include Paths
Core Include Paths
System.ArgumentException: The path is not of a legal form.
   at System.IO.Path.LegacyNormalizePath(String path, Boolean fullCheck, Int32 maxPathLength, Boolean expandShortPaths)
   at System.IO.Path.NormalizePath(String path, Boolean fullCheck, Int32 maxPathLength, Boolean expandShortPaths)
   at System.IO.Path.GetFullPathInternal(String path)
   at System.IO.DirectoryInfo.Init(String path, Boolean checkHost)
   at System.IO.DirectoryInfo..ctor(String path)
   at Visual.Micro.MiroAppAPI.SketchCompiler.CreateFileTimeListXml(String fileType, String sPath, String outputPath)
   at Visual.Micro.MiroAppAPI.SketchCompilerArduino._compile(SketchBuilder lsketch, String primaryClassName, Boolean verbose, Boolean isDebug)
   at Visual.Micro.MiroAppAPI.SketchCompilerArduino.compile(SketchBuilder lsketch, String primaryClassName, Boolean verbose, Boolean isDebug)
   at Visual.Micro.Visual.Studio.Arduino.AddInApp._CompileDo(Object oProject, Boolean IsDebugStartCommand, Boolean isRebuild, Boolean UseGdbIfAvailable)
   at Visual.Micro.Visual.Studio.Arduino.AddInApp.CompileDo(Object oProject, Boolean IsDebugStartCommand, Boolean isRebuild, Boolean UseGdbIfAvailable)
   at Visual.Micro.Visual.Studio.Arduino.AddInApp.Compile(Object oProject, Boolean IsDebugStartCommand, Boolean IsRebuild, Boolean UseGdbIfAvailable) 

Hi Tim,
The hardware was installed via the Arduino IDE.
Being a complete newbie, please would you give me instructions on how to:
1). Add index file.
2). Remove existing installation of the hardware.

This is the Verbose error:

Burning a new bootloader
Burning bootloader to board 'Pololu A-Star 328PB' using 'STK500 for Pololu A-Star 328PB'
Erase Pattern: "{cmd.path}" "-C{config.path}" "-C+{config.path2}" {erase.verbose} -p{upload.mcu} -c{protocol} {program.extra_params} -B 5 -e -Ulock:w:{bootloader.unlock_bits}:m -Uefuse:w:{bootloader.extended_fuses}:m -Uhfuse:w:{bootloader.high_fuses}:m -Ulfuse:w:{bootloader.low_fuses}:m
{runtime.tools.avrdude.path}\bin\avrdude "-C{runtime.tools.avrdude.path}/etc/avrdude.conf" 4.0.2/extra_avrdude.conf" -v -patmega328pb -cstk500 -PCOM17 -B 5 -e -Ulock:w:0xFF:m -Uefuse:w:{bootloader.extended_fuses}:m -Uhfuse:w:0xDE:m -Ulfuse:w:0xFF:m
Burn bootloader failed with an exception
	The system cannot find the file specified

Error while burning bootloader.
Burn failed 

Many Thanks

I keep getting:
"Error reading variants path"

Error after I close "Error reading variants path" Pop-Up.

Compiling 'Test_Sunday' for 'Pololu A-Star 328PB'
Build Folder: dboard_avr_a-star328PB/Release"
Summary: Header=1 Prototypes=3 Imports=0
Additional Defines:
Api: 1.1811.24-0
Sketch Book: "file:///C:/Users/Robert/Documents/Arduino"
Sketch Include Paths
Core Include Paths
System.ArgumentException: The path is not of a legal form.
   at System.IO.Path.LegacyNormalizePath(String path, Boolean fullCheck, Int32 maxPathLength, Boolean expandShortPaths)
   at System.IO.Path.NormalizePath(String path, Boolean fullCheck, Int32 maxPathLength, Boolean expandShortPaths)
   at System.IO.Path.GetFullPathInternal(String path)
   at System.IO.DirectoryInfo.Init(String path, Boolean checkHost)
   at System.IO.DirectoryInfo..ctor(String path)
   at Visual.Micro.MiroAppAPI.SketchCompiler.CreateFileTimeListXml(String fileType, String sPath, String outputPath)
   at Visual.Micro.MiroAppAPI.SketchCompilerArduino._compile(SketchBuilder lsketch, String primaryClassName, Boolean verbose, Boolean isDebug)
   at Visual.Micro.MiroAppAPI.SketchCompilerArduino.compile(SketchBuilder lsketch, String primaryClassName, Boolean verbose, Boolean isDebug)
   at Visual.Micro.Visual.Studio.Arduino.AddInApp._CompileDo(Object oProject, Boolean IsDebugStartCommand, Boolean isRebuild, Boolean UseGdbIfAvailable)
   at Visual.Micro.Visual.Studio.Arduino.AddInApp.CompileDo(Object oProject, Boolean IsDebugStartCommand, Boolean isRebuild, Boolean UseGdbIfAvailable)
   at Visual.Micro.Visual.Studio.Arduino.AddInApp.OnBeforeCommandEvent(String sGuid, Int32 ID, Object CustomIn, Object CustomOut, Boolean& CancelDefault) 

Hardware does support burn bootloader:
https://www.pololu.com/docs/0J74/5

Build error .txt file attached

Yes, I can compile in the Arduino IDE no problem.

Build error txt attached

Thanks.
I do have "Arduino 1.6/1.8" option.
I will stick to the Arduino IDE.

Thanks for your help.
I will not use vMicro but stick to Arduino IDE

I reproduced the issue in atmel studio if the (No IDE) option is selected.

It's possible you had it selected and switch to "Arduino 1.6/1.8" on the tool bar or vMicro menu but your project was not updated. I think if you use the vMicro menu to re-select Arduino 1.6/1.8 or switch to another board in the list then back again it will work okay.

The output you posted certainly shows that (No IDE) was selected.