Problem Cyberark PVWA as SP

[Yakov Revyakin]

I need to configure SAML authentication for Cyberark PVWA.

I can see that PVWA makes the request
https://testidp.hideez.com/idp/profile/SAML2/POST/SSO?SAMLRequest
=fVHLboMwEPwV5Lt......................qBifgkZLmQrxE9GrvyKM%2fr%2fpOIX

and I am able to obtain source of it:

<samlp:AuthnRequest ID="_78d938cd-c771-4b6a-8978-2f686fdc4630"
Version="2.0" IssueInstant="2019-04-19T15:40:19Z"
ProtocolBinding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST"
AssertionConsumerServiceURL="
https://components.cyberark.local/PasswordVault/api/auth/saml/logon"
xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol">
<saml:Issuer
xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">Cyberark4Hide</saml:Issuer></samlp:AuthnRequest>

As result my IdP returns the massage about Stale Request.

Log contains:
2019-04-19 18:40:21,486 - 184.170.232.52 - ERROR
[org.opensaml.profile.action.impl.DecodeMessage:73] - Profile Action
DecodeMessage: Unable to decode incoming request
org.opensaml.messaging.decoder.MessageDecodingException: This message
decoder only supports the HTTP POST method
    at
org.opensaml.saml.saml2.binding.decoding.impl.HTTPPostDecoder.doDecode(HTTPPostDecoder.java:82)

What is a stupid mistake I have done. Help please!
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