You cannot convert .xla files to .xlsx on any other Excel for add-in for that matter. XLA format is used for add-ons, plugins used to enhance the functionality of Microsoft Excel. The only thing you could potentially do is to import the .xla file to Excel and based on the imported functionalities produce or edit .xlsx speadsheet.
This conversion entry was verified by us and conversion was flagged as wrong or not possible.
Usually this happens when the conversion would try to convert different types of data between each other, such as audio to image, or it is not possible because incompatibility between programs, caused by closed file formats, very limited support etc.
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