{"record":{"id":"63f99bb099a87354","repo":"Yalantis/uCrop","slug":"load-png-failed-to-initialize-png-ptr-structu","errorCode":null,"errorMessage":"load_png(): Failed to initialize 'png_ptr' structure for file '%s'.","messagePattern":"load_png\\(\\): Failed to initialize 'png_ptr' structure for file '(.+?)'\\.","errorType":"exception","errorClass":"CImgIOException","httpStatus":null,"severity":"error","filePath":"ucrop/src/main/jni/CImg.h","lineNumber":57398,"sourceCode":"      std::FILE *nfile = file?file:cimg::fopen(nfilename,\"rb\");\n#endif\n      unsigned char pngCheck[8] = {};\n      cimg::fread(pngCheck,8,(std::FILE*)nfile);\n      if (png_sig_cmp(pngCheck,0,8)) {\n        if (!file) cimg::fclose(nfile);\n        throw CImgIOException(_cimg_instance\n                              \"load_png(): Invalid PNG file '%s'.\",\n                              cimg_instance,\n                              nfilename?nfilename:\"(FILE*)\");\n      }\n\n      // Setup PNG structures for read.\n      png_voidp user_error_ptr = 0;\n      png_error_ptr user_error_fn = 0, user_warning_fn = 0;\n      png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,user_error_ptr,user_error_fn,user_warning_fn);\n      if (!png_ptr) {\n        if (!file) cimg::fclose(nfile);\n        throw CImgIOException(_cimg_instance\n                              \"load_png(): Failed to initialize 'png_ptr' structure for file '%s'.\",\n                              cimg_instance,\n                              nfilename?nfilename:\"(FILE*)\");\n      }\n      png_infop info_ptr = png_create_info_struct(png_ptr);\n      if (!info_ptr) {\n        if (!file) cimg::fclose(nfile);\n        png_destroy_read_struct(&png_ptr,(png_infopp)0,(png_infopp)0);\n        throw CImgIOException(_cimg_instance\n                              \"load_png(): Failed to initialize 'info_ptr' structure for file '%s'.\",\n                              cimg_instance,\n                              nfilename?nfilename:\"(FILE*)\");\n      }\n      png_infop end_info = png_create_info_struct(png_ptr);\n      if (!end_info) {\n        if (!file) cimg::fclose(nfile);\n        png_destroy_read_struct(&png_ptr,&info_ptr,(png_infopp)0);\n        throw CImgIOException(_cimg_instance","sourceCodeStart":57380,"sourceCodeEnd":57416,"githubUrl":"https://github.com/Yalantis/uCrop/blob/f788b534b48c144edf786c8cddbf0e029e637804/ucrop/src/main/jni/CImg.h#L57380-L57416","documentation":"Thrown by CImg<T>::load_png() when libpng's png_create_read_struct() returns null, i.e. libpng could not allocate or initialize its core decode structure for the named file — almost always an out-of-memory condition or a libpng version/ABI problem.","triggerScenarios":"Out-of-memory or heavily fragmented heap when allocating libpng's read struct; a libpng version mismatch between headers and the linked runtime library.","commonSituations":"Memory-constrained environments (Android NDK, embedded) where allocation fails; mixing libpng headers from one version with a shared libpng of an incompatible version.","solutions":["Check available memory; reduce concurrent allocations or image workloads.","Rebuild against a consistent libpng version (headers and linked library must match).","Upgrade libpng to a current version (very old libpng versions had init issues).","If transient OOM, retry the load after freeing memory."],"exampleFix":"// before\nimg.load_png(\"big.png\"); // fails under memory pressure\n// after\nif (img.width() && img.height()) img.clear(); // release memory first\nimg.load_png(\"big.png\");","handlingStrategy":"retry","validationCode":"// no pre-call validation possible; ensure libpng is linked and heap has headroom","typeGuard":null,"tryCatchPattern":"try { img.load_png(path); }\ncatch (CImgIOException &e) {\n  std::fprintf(stderr, \"libpng init failed: %s\\n\", e.what());\n}","preventionTips":["Keep libpng headers and binaries from the same version/build","Avoid loading many large images concurrently","Monitor memory before attempting large image decodes"],"tags":["cimg","libpng","memory","initialization"],"backgroundTag":"module-init-failed","analyzedSha":"f788b534b48c144edf786c8cddbf0e029e637804","analyzedAt":"2026-09-08T08:36:04.887Z","contentChangedAt":"2026-09-08T08:36:04.887Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}