Hi @Ali ,
Per my research, I found some similar issues here:
the-item-could-not-be-indexed-successfully-because-the-item-failed-in-the-indexing-subsystem
what-is-the-source-of-this-crawl-error-the-item-could-not-be-indexed-successful
You could try the way they provided: increased the drive space of the index, reset the index, reboot the crawl server and run a full crawl.
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