{"record":{"id":"74d8cd4824174fdf","repo":"Yalantis/uCrop","slug":"get-serialize-failed-to-save-compressed-data-s","errorCode":null,"errorMessage":"get_serialize(): Failed to save compressed data, saving them uncompressed.","messagePattern":"get_serialize\\(\\): Failed to save compressed data, saving them uncompressed\\.","errorType":"console","errorClass":null,"httpStatus":null,"severity":"warning","filePath":"ucrop/src/main/jni/CImg.h","lineNumber":68759,"sourceCode":"      const char *const ptype = pixel_type(), *const etype = cimg::endianness()?\"big\":\"little\";\n      cimg_snprintf(tmpstr,tmpstr._width,\"%u %s %s_endian\\n\",_width,ptype,etype);\n      CImg<ucharT>::string(tmpstr,false).move_to(stream);\n      cimglist_for(*this,l) {\n        const CImg<T>& img = _data[l];\n        cimg_snprintf(tmpstr,tmpstr._width,\"%u %u %u %u\",img._width,img._height,img._depth,img._spectrum);\n        CImg<ucharT>::string(tmpstr,false).move_to(stream);\n        if (img._data) {\n          CImg<T> tmp;\n          if (cimg::endianness()) { tmp = img; cimg::invert_endianness(tmp._data,tmp.size()); }\n          const CImg<T>& ref = cimg::endianness()?tmp:img;\n          bool failed_to_compress = true;\n          if (is_compressed) {\n#ifdef cimg_use_zlib\n            const ulongT siz = sizeof(T)*ref.size();\n            uLongf csiz = (ulongT)compressBound(siz);\n            Bytef *const cbuf = new Bytef[csiz];\n            if (compress(cbuf,&csiz,(Bytef*)ref._data,siz))\n              cimg::warn(_cimglist_instance\n                         \"get_serialize(): Failed to save compressed data, saving them uncompressed.\",\n                         cimglist_instance);\n            else {\n              cimg_snprintf(tmpstr,tmpstr._width,\" #%lu\\n\",csiz);\n              CImg<ucharT>::string(tmpstr,false).move_to(stream);\n              CImg<ucharT>(cbuf,csiz).move_to(stream);\n              delete[] cbuf;\n              failed_to_compress = false;\n            }\n#endif\n          }\n          if (failed_to_compress) { // Write in a non-compressed way\n            CImg<charT>::string(\"\\n\",false).move_to(stream);\n            stream.insert(1);\n            stream.back().\n              assign((unsigned char*)ref._data,ref._width,ref._height,ref._depth,ref._spectrum*sizeof(T),true);\n          }\n        } else CImg<charT>::string(\"\\n\",false).move_to(stream);","sourceCodeStart":68741,"sourceCodeEnd":68777,"githubUrl":"https://github.com/Yalantis/uCrop/blob/f788b534b48c144edf786c8cddbf0e029e637804/ucrop/src/main/jni/CImg.h#L68741-L68777","documentation":"In CImgList::get_serialize() with cimg_use_zlib enabled, the zlib compress() call returned a non-zero (error) status, so the warning is emitted and the data falls back to being stored uncompressed. The serialization still succeeds; only the compression of that item failed.","triggerScenarios":"compress() fails during get_serialize(is_compressed=true), typically when the buffer to compress is huge and compressBound/allocation fails (out-of-memory for the destination buffer new Bytef[csiz] succeeding but compression failing), or zlib returning Z_STREAM_ERROR / Z_MEM_ERROR for the given sizes.","commonSituations":"Serializing extremely large images on memory-constrained devices (32-bit Android jni) where zlib cannot allocate internal state; corrupted zlib build; sizes exceeding ulongT/uLongf limits on 32-bit platforms.","solutions":["Retry with is_compressed=false to guarantee serialization succeeds uncompressed.","Free memory / process the data in smaller chunks (serialize per-image instead of a huge list).","Inspect zlib's return code path and available memory; upgrade to 64-bit build if on 32-bit NDK.","Verify the linked zlib is intact and headers match the library version."],"exampleFix":"// before\nCImg<unsigned char> buf = list.get_serialize(true);\n// after\nCImg<unsigned char> buf;\ntry { buf = list.get_serialize(true); }\ncatch (...) { buf = list.get_serialize(false); } // uncompressed fallback","handlingStrategy":"fallback","validationCode":"// pre-check rough size before compressing\nconst unsigned long long nbytes = (unsigned long long)list.size() * sizeof(T);\nif (nbytes > MAX_COMPRESS_BYTES) use_compression = false;","typeGuard":null,"tryCatchPattern":"CImg<unsigned char> buf;\ntry { buf = list.get_serialize(true); }\ncatch (const std::bad_alloc&) { buf = list.get_serialize(false); }","preventionTips":["Compress in smaller chunks instead of one giant buffer on memory-constrained devices","Monitor available memory before requesting compression of very large lists","Keep an uncompressed path available and log when it is used"],"tags":["cimg","zlib","compression","serialization","memory"],"backgroundTag":"http-request-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"}