Yalantis/uCrop · error · CImgIOException

load_png(): Failed to initialize 'end_info' structure for…

Error message

load_png(): Failed to initialize 'end_info' structure for file '%s'.

What it means

Thrown by CImg<T>::load_png() when the second png_create_info_struct() call (for the end-info structure) returns null; both previously created structures (png_ptr and info_ptr) are destroyed via png_destroy_read_struct before the exception is raised.

Solutions

Free memory and retry.
Lower peak memory usage (load images sequentially, resize before caching).
Rebuild/upgrade libpng to a consistent, current version.

Example fix

// before
img.load_png(path); // throws when end_info allocation fails
// after
img.clear();
img.load_png(path);

Defensive patterns

Strategy: try-catch

Try / catch

try { img.load_png(path); }
catch (CImgIOException &e) {
  std::fprintf(stderr, "libpng end_info init failed: %s\n", e.what());
}

Prevention

Load images one at a time in memory-constrained code
Release image buffers promptly (assign()/clear())
Keep libpng versions consistent between headers and library

When it happens

Trigger: Allocation failure while creating the third libpng structure (end_info) during load_png(); same OOM/fragmentation conditions as the other init failures.

Common situations: Low-memory processes, memory-constrained mobile/embedded builds, or near-exhausted heaps after many image operations.

Related errors

AI-assisted analysis of Yalantis/uCrop@f788b534b4 (2026-09-08). Data as JSON: /api/errors/fc78dc734344ac84. Report an issue: GitHub.

Appendix: source

Thrown at ucrop/src/main/jni/CImg.h:57416

        throw CImgIOException(_cimg_instance
                              "load_png(): Failed to initialize 'png_ptr' structure for file '%s'.",
                              cimg_instance,
                              nfilename?nfilename:"(FILE*)");
      }
      png_infop info_ptr = png_create_info_struct(png_ptr);
      if (!info_ptr) {
        if (!file) cimg::fclose(nfile);
        png_destroy_read_struct(&png_ptr,(png_infopp)0,(png_infopp)0);
        throw CImgIOException(_cimg_instance
                              "load_png(): Failed to initialize 'info_ptr' structure for file '%s'.",
                              cimg_instance,
                              nfilename?nfilename:"(FILE*)");
      }
      png_infop end_info = png_create_info_struct(png_ptr);
      if (!end_info) {
        if (!file) cimg::fclose(nfile);
        png_destroy_read_struct(&png_ptr,&info_ptr,(png_infopp)0);
        throw CImgIOException(_cimg_instance
                              "load_png(): Failed to initialize 'end_info' structure for file '%s'.",
                              cimg_instance,
                              nfilename?nfilename:"(FILE*)");
      }

      // Error handling callback for png file reading.
      if (setjmp(png_jmpbuf(png_ptr))) {
        if (!file) cimg::fclose((std::FILE*)nfile);
        png_destroy_read_struct(&png_ptr, &end_info, (png_infopp)0);
        throw CImgIOException(_cimg_instance
                              "load_png(): Encountered unknown fatal error in libpng for file '%s'.",
                              cimg_instance,
                              nfilename?nfilename:"(FILE*)");
      }
      png_init_io(png_ptr, nfile);
      png_set_sig_bytes(png_ptr, 8);

      // Get PNG Header Info up to data block.

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