It was an issue with the website.
Thanks for your support.
On another note,
Parallelization works perfectly but I has noticed a new issue:
On using a rclone copy http_remote: gdrive_remote: --files-from files1.txt --checkers 100 -vv command, with the files1.txt having around 5k links, start really late as the log is flooded with low level retry.
2019/01/10 20:03:23 DEBUG : pacer: low level retry 1/10 (error googleapi: Error 403: User Rate Limit Exceeded. Rate of requests for user exceed configured project quota. You may consider re-evaluating expected per-user traffic to the API and adjust project quota limits accordingly. You may monitor aggregate quota usage and adjust limits in the API Console: https://console.developers.google.com/apis/api/drive.googleapis.com/quotas?project=7595#####250, userRateLimitExceeded)
2019/01/10 20:03:23 DEBUG : pacer: Rate limited, sleeping for 16.885667094s (5 consecutive low level retries)
I am using my own project and the my quota limits are:
Courtesy daily quota is 1,000,000,000 QPD
Courtesy quota is 10,000 queries per 100s
Per User Limit is set to 1,000 queries per 100s