Invalid XML error for signed AuthnRequest in IE

[Asaf Peter]

Dear Shib Users,


I am implementing an SP initiated web browser SAML 2.0 SSO profile.
I am using Shibboleth IDP for testing.
When I send an unsigned AuthenRequest everything works fine. The IDP excepts the request and logs me in.
Now I am trying to add a signature to the AuthnRequest.
Surprisingly, it works fine in FireFox and Chrome, but when using IE I get an error page with message "Error decoding authentication request message".
In the IDP log I see an error "Invalid XML" --> "Encountered error parsing message into its DOM representation".
This error doesn't exist when using FF/Chrome.
Do you have an idea what might be the cause for this behavior?

Attached is an example of the AuthnRequest I send.
Thanks,
Asaf
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