dotnet/wpf · error · InvalidOperationException

SR.ZLibVersionError

Error message

SR.ZLibVersionError

What it means

ThrowIfZLibError converts zlib's VersionError (Z_VERSION_ERROR) into an InvalidOperationException carrying SR.ZLibVersionError with the runtime's zlib version string. It is thrown when the linked zlib library's version is incompatible with what ZLibNative expects — an installation/environment problem, not a data problem.

Solutions

  1. Restore the correct zlib native library bundled with the .NET/WPF runtime (reinstall the runtime or redeploy the app).
  2. Check PATH/DLL search order for a rogue zlib.dll shadowing the expected one.
  3. Ensure the app is deployed on a supported OS/runtime version where ZLibNative's expected zlib version is present.

Example fix

// before: shadowed old zlib on PATH
set PATH=C:\legacy;%PATH%

// after: let the app's bundled zlib win
set PATH=C:\app\native;%PATH%
Defensive patterns

Strategy: fallback

Try / catch

try { transform.Decompress(stream); } catch (InvalidOperationException ex) when (ex.Message.Contains("zlib")) { ReportEnvironmentProblem(ex); }

Prevention

When it happens

Trigger: Decompress or Compress invokes zlib and gets Z_VERSION_ERROR: the native zlib on the machine mismatches the version the library was compiled/bound against (e.g. an old or replaced zlib.dll/zlib native image).

Common situations: Machines with a stale or vendor-replaced zlib.dll on PATH shadowing the correct one; broken .NET/native runtime installs; deploying WPF apps without the matching native runtime components.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/05c294fa4b76f276. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/WindowsBase/MS/Internal/IO/Packaging/CompoundFile/CompoundFileDeflateTransform.cs:403

                    invalidOperation = true; break;

                case ZLibNative.ErrorCode.NeedDictionary:
                    corruption = true; break;

                case ZLibNative.ErrorCode.StreamError:
                    corruption = true; break;

                case ZLibNative.ErrorCode.DataError:
                    corruption = true; break;

                case ZLibNative.ErrorCode.MemError:
                    throw new OutOfMemoryException();

               case ZLibNative.ErrorCode.BufError:
                    invalidOperation = true; break;

                case ZLibNative.ErrorCode.VersionError:
                    throw new InvalidOperationException(SR.Format(SR.ZLibVersionError,
                        System.Text.Encoding.UTF8.GetString(ZLibVersion, 0, ZLibVersion.Length)));

                default:
                    {
                        // ErrorNo
                        throw new IOException();
                    }
            }

            if (invalidOperation)
                throw new InvalidOperationException();

            if (corruption)
                throw new FileFormatException(SR.CorruptStream);
}

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