"ASN1_CHECK_TLEN:wrong tag" when importing a PEM certificate

In my case, the error was due the string format of the PEM file. Converting directly from array to string without line breaks does not work so those had to be added.

Using powershell I managed to solve it like this:

Function Import-KeyToF5 {

    Param($F5, $KeyPEM, [string]$KeyName)

    $ManagementModetype = New-Object iControl.ManagementKeyCertificateManagementModeType
    $SecurityType = New-Object iControl.ManagementKeyCertificateSecurityType

    $F5.ManagementKeyCertificate.key_import_from_pem_v2($ManagementModetype, @($KeyName), @($KeyPem), $SecurityType, @(""), $true)

}

Convert the PEM key from an array of strings to a string with line breaks
$TempPem = $KeyPEM -join "`n"

Import-KeyToF5 -F5 $f5 -KeyPEM ([string]$TempPem) -KeyName "star.test.test.key"

Hope it helps someone!

/Patrik