I previously had a Samsung Galaxy S4. I was using a 64 GB card in that phone. A few months ago I upgraded to the S9+. I inserted the SD card from the S4 into the new phone and everything has worked fine until I ran out of space so I bought a 128 GB card. While trying to transfer data from the 64 GB card using an adapter and plugged into the USB port on my computer I was getting errors. I found a post on this forum for using the command prompt that seemed to work for a bit. After a few minutes of transferring the data the adapter which is brand new disconnects from the USB port. I have tried all the ports on this computer and another computer. I have also ran the scan disk from the properties menu within windows and no errors are found. Anyone else have any suggestions?
Sounds like there may be problems with the adapter you bought. You shouldn't really need an adapter actually.
Just put the old SD card into the phone and then connect the phone to the computer. Now move/copy all the files over to an empty folder on the computer.
Once that is done remove the phone from the computer and swap out the SD cards in the phone. Reconnect the phone to the computer and now copy or move the files from the computer over to the new SD card in the phone.
I noticed that each time the usb adapter would disconnect I would get an error for a file that were either pictures, videos, or an MP3. I would unplug the adapter and plug it back in and select skip and it would resume. I wrote down each of the files and went back and had no problem viewing or playing the files on the computer or phone. After the transfer was complete I went to each individual file and dragged each one into the proper location on the desktop copy without any problems. Seems kind of strange. Only problem now is I am wondering if something is corrupt so took my cable and plugged it into a usb port(3.0) and the new card into the adapter and dragged the files on the phone card to the new card and it is showing an estimation of 5 hours to transfer but so far no errors or usb disconnecting.