Problem after upgrade to v 2.50

Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:


Line 234:
Line 235:            //active tax provider
Line 236:            var activeTaxProvider = LoadActiveTaxProvider();
Line 237:
Line 238:            //get tax rate


Source File: c:\inetpub\wwwroot\Nop\Libraries\Nop.Services\Tax\TaxService.cs    Line: 236

What is this and what can I do to fix it?

Your plugins are not properly installed.  Google this site for  
  "Object reference not set to an instance of an object." tax provider

e.g.
https://www.nopcommerce.com/boards/t/10664/nop-2-fresh-install-object-reference-not-set-to-an-instance-of-an-object.aspx

Thank you so much :)

Same problem here. Had a working 'publish'ed site. In the last deploy, selected the 'Delete all exisitng files before publish' (was a stupid move since I did not back up any files) and since then the site has not been working. It ran the installation process by default. Realized it was because Settings.txt was missing. Copied it over. Since then this error even after I copied all the content under the Plugins directory to the published directory. Any help to fix this would really be appreciated. Version 2.5.

Thanks,
Sabari.