Background - https://community.openenergymonitor.org/t/import-from-archive-fails/27147
Reasons - https://community.openenergymonitor.org/t/import-from-archive-fails/27147/13?u=borpin
Solution;
At backup
Remove the line at backup time with something like mariadb-dump|tail +2.
On Import
Remove the line at import time with something like tail +2|mariadb.
For both, check for the word 'Sandbox' in the first line.