diff --git a/CHANGELOG.md b/CHANGELOG.md
index 04c8f48da..e1d260dd0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -72,6 +72,7 @@ BUG FIXES:
       retry from scratch [GH-4479]
   - core: line numbers show properly in Vagrantfile syntax errors
       on Windows [GH-6445]
+  - core: catch errors setting env vars on Windows [GH-6017]
   - commands/box: add command with `~` paths on Windows works [GH-5747]
   - commands/box: the update command supports CA settings [GH-4473]
   - commands/box: removing all versions and providers of a box will properly
diff --git a/lib/vagrant/bundler.rb b/lib/vagrant/bundler.rb
index e6b5aca14..7382cbc59 100644
--- a/lib/vagrant/bundler.rb
+++ b/lib/vagrant/bundler.rb
@@ -7,6 +7,7 @@ require "bundler"
 
 require_relative "shared_helpers"
 require_relative "version"
+require_relative "util/safe_env"
 
 module Vagrant
   # This class manages Vagrant's interaction with Bundler. Vagrant uses
@@ -71,12 +72,15 @@ module Vagrant
       # we add all our plugin dependencies.
       @gemfile = build_gemfile(plugins)
 
-      # Set the environmental variables for Bundler
-      ENV["BUNDLE_APP_CONFIG"] = @appconfigpath
-      ENV["BUNDLE_CONFIG"]  = @configfile.path
-      ENV["BUNDLE_GEMFILE"] = @gemfile.path
-      ENV["GEM_PATH"] =
-        "#{bundle_path}#{::File::PATH_SEPARATOR}#{@gem_path}"
+      SafeEnv.change_env do |env|
+        # Set the environmental variables for Bundler
+        env["BUNDLE_APP_CONFIG"] = @appconfigpath
+        env["BUNDLE_CONFIG"]     = @configfile.path
+        env["BUNDLE_GEMFILE"]    = @gemfile.path
+        env["GEM_PATH"] =
+          "#{bundle_path}#{::File::PATH_SEPARATOR}#{@gem_path}"
+      end
+
       Gem.clear_paths
     end
 
diff --git a/lib/vagrant/errors.rb b/lib/vagrant/errors.rb
index 341688308..d4009f347 100644
--- a/lib/vagrant/errors.rb
+++ b/lib/vagrant/errors.rb
@@ -344,6 +344,10 @@ module Vagrant
       error_key(:downloader_interrupted)
     end
 
+    class EnvInval < VagrantError
+      error_key(:env_inval)
+    end
+
     class EnvironmentNonExistentCWD < VagrantError
       error_key(:environment_non_existent_cwd)
     end
diff --git a/lib/vagrant/util/safe_env.rb b/lib/vagrant/util/safe_env.rb
new file mode 100644
index 000000000..8d7d8baf1
--- /dev/null
+++ b/lib/vagrant/util/safe_env.rb
@@ -0,0 +1,14 @@
+module Vagrant
+  module Util
+    class SafeEnv
+      # This yields an environment hash to change and catches any issues
+      # while changing the environment variables and raises a helpful error
+      # to end users.
+      def self.change_env
+        yield ENV
+      rescue Errno::EINVAL
+        raise Errors::EnvInval
+      end
+    end
+  end
+end
diff --git a/templates/locales/en.yml b/templates/locales/en.yml
index f4bde55d3..60c7e3838 100755
--- a/templates/locales/en.yml
+++ b/templates/locales/en.yml
@@ -730,6 +730,13 @@ en:
       downloader_interrupted: |-
         The download was interrupted by an external signal. It did not
         complete.
+      env_inval: |-
+        Vagrant received an "EINVAL" error while attempting to set some
+        environment variables. This is usually caused by the total size of your
+        environment variables being too large. Vagrant sets a handful of
+        environment variables to function and requires this to work. Please
+        delete some environment variables prior to executing Vagrant to
+        fix this.
       environment_locked: |-
         Vagrant attempted to acquire a lock named '%{name}', but this
         lock is being held by another instance of Vagrant already. Please