Shop '*' does not exist.","CommerceTermKey":"InvalidShop"

"@odata.context":"https://localhost:5000/Api/$metadata#Sitecore.Commerce.Core.CommandMessage","MessageDate":"2018-04 10T10:03:59.2415572Z","Code":"Error","Text":"Shop 'CommerceEngineDefaultStorefront' does not exist.","CommerceTermKey":"InvalidShop"

If you are seeing the above error in BizFx, below are the things to check:

1. Make sure that the defaultShopName in the Sitecore.Commerce.Engine.Connect.config matches with the shop name under /sitecore/Commerce/Commerce Control Panel/Storefront Settings/Storefronts. 
2. If the above step doesn't help, check /site/wwwroot/wwwroot/data/Environments/PlugIn.Content.PolicySet-1.0.0.json. Make sure that the hostname and Sitecore credentials in this config file is correct as Sitecore uses this details to make API calls for Sitecore items. If you have to make changes to this config file you would have to do commerce bootstrap to see that the changes in effect. 
3. If all the information in /site/wwwroot/wwwroot/data/Environments/PlugIn.Content.PolicySet-1.0.0.json is correct and still you are getting the same error, release the boostrap process and restart the commerce webapps / IIS site.