Yalantis/uCrop · error · CImgIOException

save_imagemagick_external(): Failed to save file '%s' with e

Error message

save_imagemagick_external(): Failed to save file '%s' with external command 'magick/convert'.

What it means

CImg::save_imagemagick_external() invokes the ImageMagick 'magick' or 'convert' executable to write formats CImg cannot handle natively. This error is thrown when the external command returns a non-zero exit status. The image was not saved.

Source

Thrown at ucrop/src/main/jni/CImg.h:63803

#define _cimg_sie_extension2 "ppm"
#endif
      CImg<charT> command(1024), filename_tmp(256);
      do {
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",cimg::temporary_path(),
                      cimg_file_separator,cimg::filenamerand(),_spectrum==1?_cimg_sie_extension1:_cimg_sie_extension2);
      } while (cimg::path_exists(filename_tmp));
#ifdef cimg_use_png
      save_png(filename_tmp);
#else
      save_pnm(filename_tmp);
#endif
      const char *magick_path = cimg::imagemagick_path();
      cimg_snprintf(command,command._width,"\"%s\" -quality %u \"%s\" \"%s\"",
                    magick_path,quality,
                    CImg<charT>::string(filename_tmp)._system_strescape().data(),
                    CImg<charT>::string(filename)._system_strescape().data());
      if (cimg::system(command,magick_path)!=0)
        throw CImgIOException(_cimg_instance
                              "save_imagemagick_external(): Failed to save file '%s' with "
                              "external command 'magick/convert'.",
                              cimg_instance,
                              filename);
      if (!cimg::path_exists(filename))
        throw CImgIOException(_cimg_instance
                              "save_imagemagick_external(): Failed to save file '%s' with "
                              "external command 'magick/convert'.",
                              cimg_instance,
                              filename);

      std::remove(filename_tmp);
      return *this;
    }

    //! Save image as a Dicom file.
    /**
       \param filename Filename, as a C-string.

View on GitHub (pinned to f788b534b4)

Solutions

Verify cimg::imagemagick_path() points to a working 'magick' or 'convert' binary and run the constructed command manually to see the actual error.
Install ImageMagick or fix the IMAGEMAGICK path configuration.
Check ImageMagick policy.xml for delegates/formats that are disabled.
Confirm the requested output format is supported by the installed ImageMagick version.
Fall back to CImg native save() or another installed tool.

Example fix

// before
img.save_imagemagick_external("out.tiff");
// after
try { img.save_imagemagick_external("out.tiff"); }
catch (CImgIOException&) { img.save_tiff("out.tiff"); } // or handle missing ImageMagick install

Defensive patterns

Strategy: try-catch

Validate before calling

bool imAvailable() {
  return std::system("magick -version > /dev/null 2>&1") == 0
      || std::system("convert -version > /dev/null 2>&1") == 0;
}

Try / catch

try {
  img.save_imagemagick_external(filename, quality);
} catch (CImgIOException& e) {
  std::fprintf(stderr, "ImageMagick save failed: %s", e.what());
  // choose native fallback or abort
}

Prevention

Install ImageMagick and confirm 'magick' or 'convert' runs in the deployment environment.
Run the failing command manually to see ImageMagick's own error text.
Review policy.xml for disabled coders/delegates.
Remember ImageMagick 6 vs 7 binary naming differences (convert vs magick).

When it happens

Trigger: Calling save_imagemagick_external(filename, quality) when: imagemagick_path() resolves to a missing or wrong binary; 'magick'/'convert' fails due to unsupported format, bad options, insufficient memory, or unreadable temp file; security policies (e.g. ImageMagick policy.xml) block the format.

Common situations: ImageMagick not installed in the deployment container; ImageMagick 7 renamed the binary to 'magick' while older scripts expect 'convert' (or vice versa); policy.xml restricting write formats; low-memory environments failing on large images.

Related errors

AI-assisted analysis of Yalantis/uCrop@f788b534b4 (2026-09-08). Data as JSON: /api/errors/3c342be63be1bbd8. Report an issue: GitHub.