How to boot fedora with out graphics to debug startup  issue ?

OR

How to debug “ "Oh no! Something has gone wrong” while booting fedora ?


Boot with out graphics by editing the grub
Check the logs for the error

Detailed steps :

1.During startup , when grub options comes
2.press e
3.this will open grub option
4.scroll
5.add 3 after quiet

like : kernel /vmlinuz-2.6.9-1.667 ro root=LABEL=/ acpi=on rhgb quiet 3

It is long but , but you need to add it

this will help you to boot with out graphics


6.log in as root

Check logs

dmesg
/var/log/Xorg.0.log
/var/log/boot.log

 grep -i error Xorg.0.log 

    (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
[   317.929] (EE) AIGLX error: dlopen of /usr/lib64/dri/i965_dri.so failed (/usr/lib64/dri/i965_dri.so: cannot open shared object file: No such file or directory)
[   317.929] (EE) AIGLX error: dlopen of /usr/lib64/dri/swrast_dri.so failed (/usr/lib64/dri/swrast_dri.so: cannot open shared object file: No such file or directory)

7.It shows file i965_dri.so  is missing
8.It was missing the physical  file location
9.Check the yum history

[root@sterinlap ~]# history | grep yum | grep remove
   62  yum remove dbus-glib-0.104-1.fc21.i686
   63  yum remove dbus-glib
  166  yum remove mesa-filesystem-10.4.7-1.20150323.fc21.x86_64

This shows that mesa drivers where removed 

10.run yum install mesa*
11.Verified the files and fedora is able to boot


12. To disable graphics or Xserver permanently  then check
/etc/inittab file  . It contains specific details for fedora 21 .

For linux ,edit /etc/inittab
id:3:initdefault from id:5:initdefault


P.S : Some times we need to verify other files in
 /var/log folder to debug boot up issues

P.S : In case  , if we need to edit /etc/fstab use mount -o remount,rw /