can't boot up after changed vm machine type from n1-standard-1 to n2-standard-2

Question

my vm can't boot up after i changed vm machine type from n1-standard-1 to n2-standard-2, why? how can i do? Will i lose all my data？ Anyone help me? please! ---serial port 1 log

[    1.689313] List of all partitions:
[    1.689957] No filesystem could mount root, tried: 
[    1.691175] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
[    1.692805] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.10.0-1062.18.1.el7.x86_64 #1
[    1.694755] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[    1.696474] Call Trace:
[    1.697152]  [<ffffffffa997b416>] dump_stack+0x19/0x1b
[    1.698071]  [<ffffffffa9974a0b>] panic+0xe8/0x21f
[    1.699102]  [<ffffffffa9f89790>] mount_block_root+0x291/0x2a0
[    1.700215]  [<ffffffffa9f897f2>] mount_root+0x53/0x56
[    1.700977]  [<ffffffffa9f89931>] prepare_namespace+0x13c/0x174
[    1.702131]  [<ffffffffa9f8940e>] kernel_init_freeable+0x222/0x249
[    1.703160]  [<ffffffffa9f88b1f>] ? initcall_blacklist+0xb0/0xb0
[    1.704197]  [<ffffffffa9969c10>] ? rest_init+0x80/0x80
[    1.705175]  [<ffffffffa9969c1e>] kernel_init+0xe/0x100
[    1.706788]  [<ffffffffa998dd1d>] ret_from_fork_nospec_begin+0x7/0x21
[    1.708216]  [<ffffffffa9969c10>] ? rest_init+0x80/0x80
[    1.710131] Kernel Offset: 0x28200000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)

Answer 1

You can follow this link to detach and reattach your boot disk to another instance, then evacuate your data.