PowerShell/PowerShell · error · PSInvalidOperationException

The file {0} could not be signed.

Error message

The file {0} could not be signed.

What it means

Thrown by Export-PSSession when signing the generated psm1 or format.ps1xml file fails for any reason. SignatureHelper.SignFile is wrapped in a try/catch that catches a generic Exception and re-throws it as PSInvalidOperationException with the failing filename, preserving the original exception as the inner exception.

Source

Thrown at src/Microsoft.PowerShell.Commands.Utility/commands/utility/ImplicitRemotingCommands.cs:3103

            {
                if (certificate == null)
                {
                    string message = ImplicitRemotingStrings.CertificateNeeded;
                    throw new PSInvalidOperationException(message);
                }
                else
                {
                    string currentFile = baseName + ".psm1";
                    try
                    {
                        SignatureHelper.SignFile(SigningOption.Default, currentFile, certificate, string.Empty, null);
                        currentFile = baseName + ".format.ps1xml";
                        SignatureHelper.SignFile(SigningOption.Default, currentFile, certificate, string.Empty, null);
                    }
                    catch (Exception e)
                    {
                        string message = StringUtil.Format(ImplicitRemotingStrings.InvalidSigningOperation, currentFile);
                        throw new PSInvalidOperationException(message, e);
                    }
                }
            }

            result.Add(baseName + ".psd1");
            FileInfo manifestFile = new(baseName + ".psd1");
            FileStream psd1 = new(
                manifestFile.FullName,
                fileMode,
                FileAccess.Write,
                FileShare.None);
            using (TextWriter writer = new StreamWriter(psd1, encoding))
            {
                GenerateManifest(writer, baseName + ".psm1", baseName + ".format.ps1xml");
                psd1.SetLength(psd1.Position);
            }

            PSPrimitiveDictionary applicationArguments = GetApplicationArguments();

View on GitHub (pinned to 3ff3c711bf)

Solutions

1. Inspect the inner exception to find the underlying SignFile failure (e.g. CryptographicException) for the real cause
2. Verify the certificate is a code-signing cert with HasPrivateKey and a Valid EnhanceKeyUsage (Code Signing), and is within its validity period
3. Ensure the generated psm1/format.ps1xml files are writable and not locked by another process
4. Re-run with a fresh cert issued specifically for code signing

Example fix

# before
Export-PSSession -Session $s -OutputModule MyMod -Certificate $tlsCert

# after
$signCert = Get-ChildItem Cert:\CurrentUser\My -CodeSigningCert |
    Where-Object { $_.NotAfter -gt (Get-Date) -and $_.HasPrivateKey }
Export-PSSession -Session $s -OutputModule MyMod -Certificate $signCert

$cert = Get-ChildItem Cert:\CurrentUser\My -CodeSigningCert |
  Where-Object { $_.HasPrivateKey -and $_.NotAfter -gt (Get-Date) }
if (-not $cert) { throw 'No valid code-signing cert available.' }

null

try { Export-PSSession -Certificate $cert @params } catch [System.Management.Automation.PSInvalidOperationException] { $inner = $_.Exception.InnerException; Write-Error "Signing failed: $($inner.Message)" }

When it happens

Trigger: Passing a -Certificate that exists in the store but is not a valid code-signing certificate, is expired/revoked, lacks a private key, or cannot write the signature to the file (path locked, read-only, missing permissions).

Common situations: Selecting a non-code-signing cert (e.g. an SSL/TLS cert) from the store; expired or not-yet-valid certificates; files held open by antivirus or another process; the cert's private key is not exportable/accessible to the current user.

Related errors

• Files cannot be loaded because running scripts is disabled o
• Unable to retrieve certificates because the thumbprint is no
• {Win32Exception(Marshal.GetLastWin32Error()).Message}
• {Win32Exception(stat).Message}
• {Win32Exception(error).Message}

AI-assisted analysis of PowerShell/PowerShell@3ff3c711bf (2026-08-13). Data as JSON: /api/errors/494e7b23534d9528. Report an issue: GitHub.