Created attachment 199831 [details] A huge (but simple) data The attached file has first 36 columns completely filled simply with the column names. Inspecting ZIP shows, that content.xml is just below 4 GB. Open the attachment; in cell AK1 put "ak"; copy the cell down (e.g., double-clicking the rectangle in the right down corner of the cell). Now try to save it. => General input/output error. The file gets saved, though; opening in 7-Zip shows, that column "Characteristics" for content.xml has "Extra_ERROR Zip64_ERROR : Descriptor UTF8". Trying to open it in Calc shows a warning: "The file 'huge.ods' is corrupt ...". Restoring the file works, having all the data. I suspect that the error is shown because of the ZIP hardening work by Michael Stahl (e.g., commit efae4fc42d5fe3c0a69757226f38efc10d101194, or some similar), and just discovered the implementation error - likely from commit abda72eeac19b18c22f57d5443c3955a463605d7, that introduced write support for Zip64.
Confirmed on windows 10 x64 with Version: 25.2.1.2 (X86_64) / LibreOffice Community Build ID: d3abf4aee5fd705e4a92bba33a32f40bc4e56f49 CPU threads: 12; OS: Windows 10 X86_64 (10.0 build 19045); UI render: Skia/Vulkan; VCL: win Calc: CL threaded When opening the saved file, LO asked if you wanna repair the file. After a while (repairing) the data fortunately is still there.