the main version is simply the software build version. it is checked by the s-on hboot to make sure that we do not roll back our firmware to what HTC considers inferior and obsolete(and in some cases,exploitable ) older software/firmware.

the first place it is checked is the "android info" text document. this is simply a small text file that is packaged inside of hboot flashable PH98IMG files. if the file fails this check,and finds the "main version" in the text document to be lower than the software on the phone,it will either return siliently to the hboot screen without explanation,or it will spit out a "main version older!" error.

here is a very basic android info text document i always use in making up PH98IMG files:
heres the one that comes inside the 2.11.605.01 RUU:

you will sometimes see different "hboot preupdate" numbers,and different things inside. i havent messed with them enuff to know(or care ) what it all means.

*you can use the directions at the end of the post to find out what your main version info is,if you need to(or maybe i should move those directions up here? hmm).

if you find yourself with a main version error you will need to do ONE of the following 2 things:

1)edit the android info text document
to alot of folks this is the easier thing to do. just like it sounds,you need to edit the main version number of the text file to be equal to or greater than your softwares main version.

i.e.,if you are on 1.02.605.6,your main version could be 1.02.605.6, 2.01.605.11, or 3.xx.xxx.x

-take the .zip file you want to flash,and unzip it. you can unzip many files without anything special in windows 7. if youre on xp,or for signed files that you cant simply right click,then "extract" you may need a utility such as 7-zip.
-open the unzipped folder and click on the android info text document to open with your favorite text editor.
-change the main version number to be = or > than yours.
-save the text document. close it. open it again for peace of mind that it changed
-rezip your file. in windows 7 this is as easy a highlighting the android info document,and any images. right click,click "send to" then "compressed(zipped) folder". older versions of windows may need a seperate utility.

your file *should* flash now.

*or

2)edit the main version on your phone

a)old school method

download this modified misc image from this threadon xda. make sure to click the "thanks" button for mrbracht.
-place the modified misc image onto your SD card,and make sure it is named " miscnew "
*next you must be booted into a rooted operating system.
-put the phone in charge only mode,plug it in if its not.
-open a cmd window as described in post 1
-change to your mini-adb_vigor directory
cd c:\mini-adb_vigor

-make sure youre connected
adb devices

-open a root shell. have your phone awake and unlocked before doing this,as sometimes you will have to allow a supeuser pop up if youre running a stock rom.

adb shell (prompt should change to a # .if your prompt only changes to a $,then type su )

-write the new misc image:
dd if=/sdcard2/miscnew.img of=/dev/block/mmcblk0p24

-exit out of your adb shell
exit (may have to type this a second time)

-reboot
adb reboot

your main version should now be set to 1.00.000.0. you should now be able to flash literally anything without altering stupid text documents

heres what it will look like(red are my inputs):
b) flash "main version low zip" method

credits:
drellisdee for coming up with this main version tool
con247 for using it to create a flashable zip to change main version to a generic 1.00.000.0 in this post

*assumtions:
-that you rooted with the guide in this first post,and thus have adb/fastboot set up in the "mini-adb_vigor" file on the root of your C drive.
-that you are using amon ra recovery image

1)download this file:
- main version tool

2)change main version:

-place "SetMainVersionLOW.zip" on the root of your phones SD card

-open a cmd window as described in post 1

-change to mini-adb directory:
cd c:\mini-adb_vigor

-check connectivity
adb devices

-boot to bootloader
adb reboot bootloader

-launch recovery
fastboot boot recovery-ra-vigor-3.14-gnm.img

-using the phones amon ra menu options,flash "SetMainVersionLOW.zip" just like you would any other rom. no need to wipe anything,just flash it.

-boot back into bootloader
adb reboot bootloader

-check main version
fastboot getvar all

-if your main version is now 1.00.000.0 then procede with whatever you needed to change the main version for




*how to check your main version
-open a cmd window as described in post 1
-change to mini-adb directory:
cd c:\mini-adb_vigor

-check connection
adb devices

-boot to fastboot
adb reboot bootloader

-enter:
fastboot getvar all

-check your mainver number

heres what it will look like(red are my inputs,blue are simply additional comments):