"Suddenly I can't save files on my external hard drive anymore!"に関する回答I have a WD Passport HD with 4TB. When I bought it, I partitioned it, so that I could use one partition for Time machine, and the other for extra files. Now the Time Machine partition is writable, but the other partition is readable only. I cannot copy files onto it anymore. It may be due to an upgrade in my OS. I’m running High Sierra. I’ve tried to change permissions in the INFO section of the partition, but everything is greyed out. How can I get read and write permissions without having to reformat the whole HD? Thanks for your help.