''The source file is corrupt'' and ''The value cannot be null'' errors

After finishing a project (Trados 2022) , I am not allowed to save and download the completed work.
I get either the error ''The source file is corrupt'' or the error ''The value cannot be null'' (alternately. Sometimes one sometimes the other).
Could someone please help me to solve it. I am really struggling and tired.

Thank you for any help you can offer me.

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