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Win 10 keeps losing dual boot info


Hi there. I had been dual-booting between win 7 and win 10. That part was working fine, but I was unhappy wth my win 10 installation. So I erased the partition and reinstalled it. First sign of trouble: It didn't detect my win 7 installation. But it was there (I already got files from it). I installed EasyBCD, added the entry for win 7, saved the set up, then wrote the MBR with the new entry. Went to MSConfig to doublecheck. Both entries were there.
I restarted, and it booted straight into Win 10. EasyBCD no longer had the win 7 entry. Neither did MSConfig. Went through the whole process again. Same problem at restart. And it wasn't fastboot, I could see the BIOS entry, etc.
What went wrong? Thanks in advance for your help.
P.S. By Windows 10 I mean Build 10049.

When you wiped out Win 10, did you check if Win 7 boots up? You have to make sure that the host OS is booting up as normal before installing the second OS.

Thanks, badrobot. No, I did not make sure. After doing stuff like that many times with no problem, I never thought of it.

Hi there. I had been dual-booting between win 7 and win 10. That part was working fine, but I was unhappy wth my win 10 installation. So I erased the partition and reinstalled it. First sign of trouble: It didn't detect my win 7 installation. But it was there (I already got files from it). I installed EasyBCD, added the entry for win 7, saved the set up, then wrote the MBR with the new entry. Went to MSConfig to doublecheck. Both entries were there.
I restarted, and it booted straight into Win 10. EasyBCD no longer had the win 7 entry. Neither did MSConfig. Went through the whole process again. Same problem at restart. And it wasn't fastboot, I could see the BIOS entry, etc.
What went wrong? Thanks in advance for your help.
P.S. By Windows 10 I mean Build 10049.
It's probably still there, press and hold Shift while clicking Restart to see if you get 'Chose another operating system' option.


Thanks, badrobot. No, I did not make sure. After doing stuff like that many times with no problem, I never thought of it.

Win 10 always sets itself as a default but you can always change it in msconfig. The problem is if 7 has boot problem before installing 10, you will not get dual boot options and will go straight to 10.

Have you tried to repair windows7 with Startup repair by booting from 7 install media. You must have deleted your active partition when you installed 10.

Thanks, Edwin. Holding Shift with Restart got me into Startup Repair. But no, it didn't give me the option of Windows 7.

Thanks, Charlie, for the tip of repairing Windows 7. I will try that today and post back.

Code:
bcdboot C:Windows
Type that in an elevated command prompt and it should take care of your boot files. Do the same with your drive letter for the other installation.

Thanks, cyberrufus. Didn't need that.
I did what Charlie suggested, and repaired the win 7 installation. Everything is ok now.

Thank you all guys, for your tips.

You can also use: Download EasyBCD - MajorGeeks to resolve boot issues and boot order.

Win 10 keeps losing dual boot info