diff --git a/PowerFGT/Public/Connection.ps1 b/PowerFGT/Public/Connection.ps1
index efb3c62b..7b16fa21 100644
--- a/PowerFGT/Public/Connection.ps1
+++ b/PowerFGT/Public/Connection.ps1
@@ -127,6 +127,8 @@ function Connect-FGT {
         [Parameter(Mandatory = $false)]
         [string]$license,
         [Parameter(Mandatory = $false)]
+        [switch]$oldauth = $false,
+        [Parameter(Mandatory = $false)]
         [string[]]$vdom,
         [Parameter(Mandatory = $false)]
         [boolean]$DefaultConnection = $true
@@ -186,6 +188,86 @@ function Connect-FGT {
         if ($ApiToken) {
             $headers += @{ "Authorization" = "Bearer $ApiToken" }
         }
+        elseif ( $oldauth -ne $true ) {
+            #If there is a password (and a user), create a credentials
+            if ($Password) {
+                $Credentials = New-Object System.Management.Automation.PSCredential($Username, $Password)
+            }
+            #Not Credentials (and no password)
+            if ($null -eq $Credentials) {
+                $Credentials = Get-Credential -Message 'Please enter administrative credentials for your FortiGate'
+            }
+            # new api auth method (Seen FortiOS 6.4+)
+            $postParams = @{
+                username  = $Credentials.username;
+                password  = $Credentials.GetNetworkCredential().Password;
+                secretkey = $Credentials.GetNetworkCredential().Password;
+            }
+
+            $uri = $url + "api/v2/authentication"
+            Write-Verbose $uri
+
+            try {
+                $irmResponse = Invoke-RestMethod $uri -Method POST -Body ($postParams | ConvertTo-Json) -SessionVariable FGT @invokeParams
+            }
+            catch {
+                if ($_.Exception.Response.StatusCode.Value__ -eq "401" ) {
+                    throw "Not supported API Authentication method on this FortiGate (try use -oldauth parameter)"
+                }
+                else {
+                    Show-FGTException $_
+                    throw "Unable to connect to FortiGate"
+                }
+
+            }
+
+            Write-verbose $irmResponse
+            #Following FortiOS version it is status_code or status...
+            if ($irmResponse.status_code) {
+                $status = $irmResponse.status_code
+            }
+            else {
+                $status = $irmResponse.status
+            }
+
+            switch ($status) {
+                '-1' {
+                    throw "Log in failure. Most likely an incorrect username/password combo"
+                }
+                '-4' {
+                    #with FortiOS 7.6.3+, no longer warning when locked account...
+                    throw "Admin is now locked out (Please retry in 60 seconds)"
+                }
+                '5' {
+                    #no thing, it is good ! continue
+                }
+                '6' {
+                    #no thing, it is good ! continue (with FortiOS 7.6.3+)
+                }
+                default {
+                    throw "Authentication failure. Status code: $status $($irmResponse.status_message)"
+                }
+            }
+
+            #Search crsf cookie and to X-CSRFTOKEN
+            $cookies = $FGT.Cookies.GetCookies($uri)
+            foreach ($cookie in $cookies) {
+                if ($cookie.name -like "ccsrf*" ) {
+                    #before 7.6 it was ccsrftoken_port_xxxx, from 7.6.3+ it is ccsrf_token_port_xxxx
+                    $cookie_csrf = $cookie.value
+                }
+            }
+
+            # throw if don't found csrf cookie...
+            if ($null -eq $cookie_csrf) {
+                throw "Unable to found CSRF Cookie"
+            }
+
+            #Remove extra "quote"
+            $cookie_csrf = $cookie_csrf -replace '["]', ''
+            #Add csrf cookie to header (X-CSRFTOKEN)
+            $headers += @{"X-CSRFTOKEN" = $cookie_csrf }
+        }
         else {
             #If there is a password (and a user), create a credentials
             if ($Password) {
@@ -210,8 +292,9 @@ function Connect-FGT {
             if ( $iwrResponse.Content[0] -eq "{") {
                 $json = $iwrResponse.Content | ConvertFrom-Json
                 $status = $json.status
-            } else {
-                 $status = $iwrResponse.Content[0]
+            }
+            else {
+                $status = $iwrResponse.Content[0]
             }
 
             #check if need token...
@@ -350,6 +433,7 @@ function Connect-FGT {
         $connection.invokeParams = $invokeParams
         $connection.vdom = $vdom
         $connection.serial = $version.serial
+        $connection.oldauth = $oldauth
         if ($version.results.current.major) {
             $connection.version = [version]"$($version.results.current.major).$($version.results.current.minor).$($version.results.current.patch)"
         }
@@ -446,10 +530,17 @@ function Disconnect-FGT {
 
     Process {
 
-        $url = "logout"
+        $method = "DELETE"
+        $url = "api/v2/authentication"
+
+        #old auth use logout url
+        if ($connection.oldauth) {
+            $url = "logout"
+            $method = "POST"
+        }
 
         if ($PSCmdlet.ShouldProcess($connection.server, 'Proceed with removal of FortiGate connection ?')) {
-            $null = invoke-FGTRestMethod -method "POST" -uri $url -connection $connection
+            $null = invoke-FGTRestMethod -method $method -uri $url -connection $connection
             if (Test-Path variable:global:DefaultFGTConnection) {
                 Remove-Variable -name DefaultFGTConnection -scope global
             }
diff --git a/Tests/common.ps1 b/Tests/common.ps1
index 9f2cbd87..aad096c0 100644
--- a/Tests/common.ps1
+++ b/Tests/common.ps1
@@ -100,6 +100,13 @@ else {
 $invokeParams.add('SkipCertificateCheck', $SkipCertificateCheck)
 $invokeParams.add('httpOnly', $httpOnly)
 $invokeParams.add('port', $port)
+if ($oldauth -eq "true") {
+    $script:oldauth = $true
+}
+else {
+    $script:oldauth = $false
+}
+$invokeParams.add('oldauth', $oldauth)
 
 #Make a connection for check info and store version (used for some test...)
 $fgt = Connect-FGT @invokeParams
diff --git a/Tests/credential.ci.ps1 b/Tests/credential.ci.ps1
index ba3779b9..70d8473e 100644
--- a/Tests/credential.ci.ps1
+++ b/Tests/credential.ci.ps1
@@ -9,6 +9,7 @@
 $script:ipaddress = $env:IPADDRESS
 $script:login = $env:LOGIN
 $script:password = $env:PASSWORD
+$script:oldauth = $env:OLDAUTH
 $script:httpOnly = $false
 $script:SkipCertificateCheck = $true
 $script:ci = $true
diff --git a/Tests/credential.example.ps1 b/Tests/credential.example.ps1
index f3ed7e9f..c9c776ea 100644
--- a/Tests/credential.example.ps1
+++ b/Tests/credential.example.ps1
@@ -14,6 +14,7 @@ $script:httpOnly = $true
 #$script:apitoken = "yourtoken"
 $script:SkipCertificateCheck = $true
 $script:ci = $false
+$script:oldauth = $false
 
 #default settings use for test, can be override if needed...
 $script:pester_address1 = "pester_address1"
diff --git a/Tests/integration/Connection.Tests.ps1 b/Tests/integration/Connection.Tests.ps1
index 99f8b41c..43cb301d 100644
--- a/Tests/integration/Connection.Tests.ps1
+++ b/Tests/integration/Connection.Tests.ps1
@@ -7,7 +7,7 @@
 
 Describe  "Connect to a FortiGate (using HTTP)" {
     It "Connect to a FortiGate (using HTTP) and check global variable" -Skip:( -not $httpOnly ) {
-        Connect-FGT $ipaddress -Username $login -password $mysecpassword -httpOnly -port $port
+        Connect-FGT $ipaddress -Username $login -password $mysecpassword -httpOnly -port $port -oldauth:$oldauth
         $DefaultFGTConnection | Should -Not -BeNullOrEmpty
         $DefaultFGTConnection.server | Should -Be $ipaddress
         $DefaultFGTConnection.invokeParams | Should -Not -BeNullOrEmpty
@@ -23,11 +23,11 @@ Describe  "Connect to a FortiGate (using HTTP)" {
         $DefaultFGTConnection | Should -Be $null
     }
     It "Connect to a FortiGate (using HTTP) with wrong password" -Skip:( -not $httpOnly ) {
-        { Connect-FGT $ipaddress -Username $login -password $mywrongpassword -httpOnly -port $port } | Should -throw "Log in failure. Most likely an incorrect username/password combo"
+        { Connect-FGT $ipaddress -Username $login -password $mywrongpassword -httpOnly -port $port -oldauth $oldauth } | Should -throw "Log in failure. Most likely an incorrect username/password combo"
     }
     #TODO: Connect using MFA (token) and/or need to change password (admin expiration)
     It "Connect to a Fortigate (using HTTP) with apiToken" -Skip:( -not ($apitoken -ne $null -and $httpOnly -eq $true -and $fgt_version -ge "7.0.0")) {
-        Connect-FGT -Server $ipaddress -ApiToken $apitoken -port $port -httpOnly
+        Connect-FGT -Server $ipaddress -ApiToken $apitoken -port $port -httpOnly -oldauth:$oldauth
         $DefaultFGTConnection | Should -Not -BeNullOrEmpty
         $DefaultFGTConnection.server | Should -Be $ipaddress
         $DefaultFGTConnection.invokeParams | Should -Not -BeNullOrEmpty
@@ -42,7 +42,7 @@ Describe  "Connect to a FortiGate (using HTTP)" {
 
 Describe "Connect to a fortigate (using HTTPS)" {
     It "Connect to a FortiGate (using HTTPS and -SkipCertificateCheck) and check global variable" -Skip:($httpOnly) {
-        Connect-FGT $ipaddress -Username $login -password $mysecpassword -SkipCertificateCheck -port $port
+        Connect-FGT $ipaddress -Username $login -password $mysecpassword -SkipCertificateCheck -port $port -oldauth:$oldauth
         $DefaultFGTConnection | Should -Not -BeNullOrEmpty
         $DefaultFGTConnection.server | Should -Be $ipaddress
         $DefaultFGTConnection.invokeParams | Should -Not -BeNullOrEmpty
@@ -60,11 +60,11 @@ Describe "Connect to a fortigate (using HTTPS)" {
     #This test only work with PowerShell 6 / Core (-SkipCertificateCheck don't change global variable but only Invoke-WebRequest/RestMethod)
     #This test will be fail, if there is valid certificate...
     It "Connect to a FortiGate (using HTTPS) and check global variable" -Skip:("Desktop" -eq $PSEdition -Or $httpOnly) {
-        { Connect-FGT $ipaddress -Username $login -password $mysecpassword } | Should -throw "Unable to connect (certificate)"
+        { Connect-FGT $ipaddress -Username $login -password $mysecpassword -oldauth:$oldauth } | Should -throw "Unable to connect (certificate)"
     }
 
     It "Connect to a FortiGate (using HTTPS) with wrong password" -Skip:($httpOnly) {
-        { Connect-FGT $ipaddress -Username $login -password $mywrongpassword -port $port -SkipCertificateCheck:$SkipCertificateCheck } | Should -throw "Log in failure. Most likely an incorrect username/password combo"
+        { Connect-FGT $ipaddress -Username $login -password $mywrongpassword -port $port -SkipCertificateCheck:$SkipCertificateCheck -oldauth:$oldauth } | Should -throw "Log in failure. Most likely an incorrect username/password combo"
     }
 
     It "Connect to a Fortigate (using HTTPS) with apiToken" -Skip:($apitoken -eq $null -Or $httpOnly) {
@@ -79,6 +79,10 @@ Describe "Connect to a fortigate (using HTTPS)" {
         $DefaultFGTConnection.version | Should -Not -BeNullOrEmpty
         $DefaultFGTConnection.serial | Should -Not -BeNullOrEmpty
     }
+
+    It "Connect to a FortiGate (using HTTPS) to old (before FortiOS 6.4 without -oldauth)" -Skip:($httpOnly -or $fgt_version -ge "6.4.0" ) {
+        { Connect-FGT $ipaddress -Username $login -password $mysecpassword -SkipCertificateCheck -port $port } | Should -throw "Not supported API Authentication method on this FortiGate (try use -oldauth parameter)"
+    }
 }
 
 Describe "Connect to a FortiGate (with post-login-banner enable)" {
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index 9fddd0dc..098ed22c 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -23,24 +23,31 @@ stages:
             FortiOS60:
               name: "FortiOS 6.0"
               IPADDRESS: $(IPADDRESS_60)
+              OLDAUTH: true
             FortiOS62:
               name: "FortiOS 6.2"
               IPADDRESS: $(IPADDRESS_62)
+              OLDAUTH: true
             FortiOS64:
               name: "FortiOS 6.4"
               IPADDRESS: $(IPADDRESS_64)
+              OLDAUTH: false
             FortiOS70:
               name: "FortiOS 7.0"
               IPADDRESS: $(IPADDRESS_70)
+              OLDAUTH: false
             FortiOS72:
               name: "FortiOS 7.2"
               IPADDRESS: $(IPADDRESS_72)
+              OLDAUTH: false
             FortiOS74:
               name: "FortiOS 7.4"
               IPADDRESS: $(IPADDRESS_74)
+              OLDAUTH: false
             FortiOS76:
               name: "FortiOS 7.6"
               IPADDRESS: $(IPADDRESS_76)
+              OLDAUTH: false
         steps:
           - task: PowerShell@2
             displayName: "Test PowerShell Core $(name)"
@@ -62,6 +69,7 @@ stages:
               LOGIN: $(LOGIN)
               IPADDRESS: $(IPADDRESS)
               PASSWORD: $(PASSWORD)
+              OLDAUTH: $(OLDAUTH)
           - task: PublishTestResults@2
             inputs:
               testResultsFormat: "NUnit"
@@ -79,24 +87,31 @@ stages:
             FortiOS60:
               name: "FortiOS 6.0"
               IPADDRESS: $(IPADDRESS_60)
+              OLDAUTH: true
             FortiOS62:
               name: "FortiOS 6.2"
               IPADDRESS: $(IPADDRESS_62)
+              OLDAUTH: true
             FortiOS64:
               name: "FortiOS 6.4"
               IPADDRESS: $(IPADDRESS_64)
+              OLDAUTH: false
             FortiOS70:
               name: "FortiOS 7.0"
               IPADDRESS: $(IPADDRESS_70)
+              OLDAUTH: false
             FortiOS72:
               name: "FortiOS 7.2"
               IPADDRESS: $(IPADDRESS_72)
+              OLDAUTH: false
             FortiOS74:
               name: "FortiOS 7.4"
               IPADDRESS: $(IPADDRESS_74)
+              OLDAUTH: false
             FortiOS76:
               name: "FortiOS 7.6"
               IPADDRESS: $(IPADDRESS_76)
+              OLDAUTH: false
         steps:
           - task: PowerShell@2
             displayName: "Test PowerShell Core $(name)"
@@ -118,6 +133,7 @@ stages:
               LOGIN: $(LOGIN)
               IPADDRESS: $(IPADDRESS)
               PASSWORD: $(PASSWORD)
+              OLDAUTH: $(OLDAUTH)
           - task: PowerShell@2
             displayName: "Test PowerShell 5 $(name)"
             inputs:
@@ -138,6 +154,7 @@ stages:
               LOGIN: $(LOGIN)
               IPADDRESS: $(IPADDRESS)
               PASSWORD: $(PASSWORD)
+              OLDAUTH: $(OLDAUTH)
           - task: PublishTestResults@2
             inputs:
               testResultsFormat: "NUnit"