Ole Error 800A03EC is a well-known Error, and the cause of the Error is widely debated.
Recently, I have been using XLReport VCL to generate EXcel reports. This control (2003) was a great piece of Delphi7. Unfortunately, the following part did not update it for any reason, and even the company was cancelled.
Encountered this error Delphi developers are not a few, but have not been able to say why, have not been solved!
https://www.board4all.biz/threads/xlreport-excel-2013-ole-error-800a03ec.611247/
Through the debug tracking the problem is that call xlEngine. Procedure of pas units TxlExcelDataSource. GetRangeInfo
When ir.unmerge is executed, Ole Error 800A03EC, a nasty exception, occurs. The general view is caused by the upgrade of Excel version, but the original company has abandoned this product, no one can maintain and modify the source code, it is a pity, so excellent VCL.
Because there is source code, so after foreign experts modify, Delphi XE2 subsequent version can be installed and used, after constant exploration, finally solved the Ole Error 800A03EC exception, for the report development work brought high efficiency!