I am uploading new items using .csv template. When I tried to upload with 100 items, it is working but more than 100 items, getting error “Valid row (#21) 265458900304”.
I would suggest - as I am also uploading and importing lots of data at the moment to examine Row 21 in Detail. I encountered Problems with special Characters - which I see in your products.
I tried with removing all wild characters and upload but did not worked. I found some of the records were duplicate which I removed and it worked.
So my learning is that, check the error log, work on error messages (if record is duplicate, remove record from file) then system will allow to upload all the records.