Amara upload error and how to solve it

Sometimes Amara's upload error is hard to solve. Because the error message is empty. I will show some of them.

Extra comma (or maybe something else) in the time code

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  This is one error case, there is no error description (orange bar is empty). There is a message: "Our site accepsts SRT, SSA, SBV, DXXP, and TXT format. Only files ending in .srt, .ssa, .sbv, .dsxp, .txt, or .xml (for dfxp) are accepted." This suggests the file extension is wrong. However, you can see the file extension is '.srt'.
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  The reason is an extra comma, at time code 82. This makes the above error.