diff --git a/scripts/Start-EditorServices.ps1 b/scripts/Start-EditorServices.ps1
index ff7198aff2..ce2545d0fa 100644
--- a/scripts/Start-EditorServices.ps1
+++ b/scripts/Start-EditorServices.ps1
@@ -65,24 +65,38 @@ param(
     $ConfirmInstall
 )
 
-function WriteSessionFile($sessionInfo) {
-    ConvertTo-Json -InputObject $sessionInfo -Compress | Set-Content -Force -Path "$SessionDetailsPath" -ErrorAction Stop
+function ExitWithError($errorString) {
+
+    Write-Host -ForegroundColor Red "`n`n$errorString"
+
+    # Sleep for a while to make sure the user has time to see and copy the
+    # error message
+    Start-Sleep -Seconds 300
+
+    exit 1;
 }
 
 # Are we running in PowerShell 2 or earlier?
 if ($PSVersionTable.PSVersion.Major -le 2) {
-    $resultDetails = @{
-        "status" = "failed"
-        "reason" = "unsupported"
-        "powerShellVersion" = $PSVersionTable.PSVersion.ToString()
-    };
+    # No ConvertTo-Json on PSv2 and below, so write out the JSON manually
+    "{`"status`": `"failed`", `"reason`": `"unsupported`", `"powerShellVersion`": `"$($PSVersionTable.PSVersion.ToString())`"}" |
+        Set-Content -Force -Path "$SessionDetailsPath" -ErrorAction Stop
 
-    # Notify the client that the services have started
-    WriteSessionFile $resultDetails
+    ExitWithError "Unsupported PowerShell version $($PSVersionTable.PSVersion), language features are disabled."
+}
 
-    Write-Host "Unsupported PowerShell version $($PSVersionTable.PSVersion), language features are disabled.`n"
+function WriteSessionFile($sessionInfo) {
+    ConvertTo-Json -InputObject $sessionInfo -Compress | Set-Content -Force -Path "$SessionDetailsPath" -ErrorAction Stop
+}
+
+if ($host.Runspace.LanguageMode -eq 'ConstrainedLanguage') {
+    WriteSessionFile @{
+        "status" = "failed"
+        "reason" = "languageMode"
+        "detail" = $host.Runspace.LanguageMode.ToString()
+    }
 
-    exit 0;
+    ExitWithError "PowerShell is configured with an unsupported LanguageMode (ConstrainedLanguage), language features are disabled."
 }
 
 # Are we running in PowerShell 5 or later?
@@ -240,5 +254,5 @@ catch [System.Exception] {
         $e = $e.InnerException;
     }
 
-    Write-Error ("`r`nCaught error while waiting for EditorServicesHost to complete:`r`n" + $errorString)
+    ExitWithError ("Caught error while waiting for EditorServicesHost to complete:`r`n" + $errorString)
 }
\ No newline at end of file
diff --git a/src/session.ts b/src/session.ts
index fad251e751..fdb9d1e48f 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -327,6 +327,10 @@ export class SessionManager {
                                 this.setSessionFailure(
                                     `PowerShell language features are only supported on PowerShell version 3 and above.  The current version is ${sessionDetails.powerShellVersion}.`)
                             }
+                            else if (sessionDetails.reason === "languageMode") {
+                                this.setSessionFailure(
+                                    `PowerShell language features are disabled due to an unsupported LanguageMode: ${sessionDetails.detail}`);
+                            }
                             else {
                                 this.setSessionFailure(`PowerShell could not be started for an unknown reason '${sessionDetails.reason}'`)
                             }
diff --git a/src/utils.ts b/src/utils.ts
index 0db0a5619b..6dcb0bbf18 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -57,6 +57,7 @@ export function getPipePath(pipeName: string) {
 export interface EditorServicesSessionDetails {
     status: string;
     reason: string;
+    detail: string;
     powerShellVersion: string;
     channel: string;
     languageServicePort: number;