Question Error 500 when post 1 long body, but 2 working fine

I got fresh install Kunena with latest Joomla below is my report

When I create a New Post with a long body
Words count 1010, Characters with space 7242, Paragraphs 121, Line 179
I got 500 server error,

But When I cut its and half and make 2 posts, then it's working fine, I'm not sure what cause this limitation?

Thanks

Database collation check: ✔ The collation of your table fields are correct

Joomla! SEF: Enabled | Joomla! SEF rewrite: Disabled | FTP layer: Disabled |

This message contains confidential information

htaccess: Exists | PHP environment: Max execution time: 90 seconds | Max execution memory: 64M | Max file upload: 64M

Kunena menu details:

Warning: Spoiler!

ID	Name	Menutype	Link	Path	In trash
143	Forum	kunenamenu	view=home&defaultmenu=145	forum	No
144	Index	kunenamenu	view=category&layout=list	forum/index	No
145	Recent Topics	kunenamenu	view=topics&mode=replies	forum/recent	No
146	Unread	kunenamenu	view=topics&layout=unread	forum/unread	No
147	New Topic	kunenamenu	view=topic&layout=create	forum/newtopic	No
148	No Replies	kunenamenu	view=topics&mode=noreplies	forum/noreplies	No
149	My Topics	kunenamenu	view=topics&layout=user&mode=default	forum/mylatest	No
150	Profile	kunenamenu	view=user	forum/profile	No
151	Help	kunenamenu	view=misc	forum/help	No
152	Search	kunenamenu	view=search	forum/search	No
153	Diễn Đàn	mainmenu	view=home&defaultmenu=143	dien-dan	No

Joomla default template details : yootheme | author: YOOtheme | version: 1.17.0 | creationdate: December 2018

Kunena default template details : NTS KTrend | author: Nice Theme Store | version: 1.0.4 | creationdate: 2019-03-02

Kunena template params:

Warning: Spoiler!

DefaultCategoryicon
profileIconset	default
DefaultIconset	default
editorIconset	default
bootstrap	1
icomoon	1
tooltips	1
borderless	1
SubjectLengthMessage	80
fullactions	1
quick	0
displayMenu	1
displayDropdownMenu	1
displayDropdownContent	1
displayModule	1
displayBreadcrumb	1
displayAnnouncement	1
displayFooter	1
avatarPosition	left
avatarType	none
labels	0
whoisonlineName	default
formRecover	0
topicicontype	fa
fontawesome	1
socialshare	0
socialsharetag
socialtheme	classic
optional_username	0
writeaccess	0
localstorage	0
primaryColor	#007bff
forumLinkcolor	#007bff
forumLinkHoverColor	#007bff
inactiveTabcolor	#6c757d
hoverTabcolor	#007bff
activeTabcolor	#007bff
btnBgColor	#dee2e6
btnColor	#495057
btnModBg	#7e57c2
btnModColor	#ffffff
forumHeadercolor	#6c757d
forumHeaderHovercolor	#007bff
categoryIconColor	#6c757d
announcementBoxbgcolor	#fff3e0
announcementColor	#5c5c5c
enableSkinner	0
editor	0
video	1
maps	1
emoticons	1
twitter	1
ebay	1
link	1
picture	1
hide	1
spoiler	1
table	1
code	1
quote	1
divider	1
instagram	1
soundcloud	1
confidential	1
hr	1
listitem	1
supscript	1
subscript	1
numericlist	1
bulletedlist	1
alignright	1
alignleft	1
center	1
underline	1
italic	1
bold	1
strikethrough	1
colors	1
size	1
wysibb	bold,italic,underline,strike,sup,sub,justifyleft,justifycenter,justifyright,|,img,video,link,|,bullist,numlist,|,fontcolor,fontsize,fontfamily,|,quote,code,table,removeFormat
avatarSizeX	40
avatarSizeY	90
avatarSizeXThumb	36
avatarSizeYThumb	36
avatarSizeXWelcome	72
avatarSizeYWelcome	72
avatarSizeXList	36
avatarSizeYList	36
avatarSizeXPost	144
avatarSizeYPost	144
avatarSizeXProfile	200
avatarSizeYProfile	200
templatebyText
templatebyName
templatebyLink

Kunena version detailed: Kunena 5.1.10.1 | 2019-03-04 [ Janus ]
| Kunena detailed configuration:

Warning: Spoiler!

Kunena config settings:
board_offline	0
enablerss	1
threads_per_page	20
messages_per_page	6
messages_per_page_search	15
showhistory	1
historylimit	6
shownew	1
disemoticons	0
template	nts_ktrend
showannouncement	1
avataroncat	0
catimagepath	category_images
showchildcaticon	1
rtewidth	450
rteheight	300
enableforumjump	1
reportmsg	1
username	1
askemail	0
showemail	0
showuserstats	1
showkarma	1
useredit	1
useredittime	0
useredittimegrace	600
editmarkup	1
allowsubscriptions	1
subscriptionschecked	1
allowfavorites	1
maxsubject	50
maxsig	300
regonly	0
pubwrite	0
floodprotection	30
mailmod	0
mailadmin	0
captcha	0
mailfull	1
allowavatarupload	1
allowavatargallery	1
avatarquality	75
avatarsize	2048
imageheight	800
imagewidth	800
imagesize	150
filetypes	txt,rtf,pdf,zip,tar.gz,tgz,tar.bz2
filesize	32000
showranking	1
rankimages	1
userlist_rows	30
userlist_online	1
userlist_avatar	1
userlist_posts	1
userlist_karma	1
userlist_email	0
userlist_joindate	1
userlist_lastvisitdate	1
userlist_userhits	1
latestcategory	0
showstats	1
showwhoisonline	1
showgenstats	1
showpopuserstats	1
popusercount	5
showpopsubjectstats	1
popsubjectcount	5
showspoilertag	1
showvideotag	1
showebaytag	1
trimlongurls	1
trimlongurlsfront	40
trimlongurlsback	20
autoembedyoutube	1
autoembedebay	1
ebaylanguagecode	en-us
sessiontimeout	1800
highlightcode	0
rss_type	topic
rss_timelimit	month
rss_limit	100
rss_included_categories
rss_excluded_categories
rss_specification	rss2.0
rss_allow_html	1
rss_author_format	name
rss_author_in_title	1
rss_word_count	0
rss_old_titles	1
rss_cache	900
defaultpage	recent
default_sort	asc
sef	1
showimgforguest	1
showfileforguest	1
pollnboptions	4
pollallowvoteone	1
pollenabled	1
poppollscount	5
showpoppollstats	1
polltimebtvotes	00:15:00
pollnbvotesbyuser	100
pollresultsuserslist	1
allow_user_edit_poll	0
maxpersotext	50
ordering_system	mesid
post_dateformat	ago
post_dateformat_hover	datetime
hide_ip	1
imagetypes	jpg,jpeg,gif,png
checkmimetypes	1
imagemimetypes	image/jpeg,image/jpg,image/gif,image/png
imagequality	50
thumbheight	32
thumbwidth	32
hideuserprofileinfo	put_empty
boxghostmessage	0
userdeletetmessage	0
latestcategory_in	1
topicicons	1
debug	1
catsautosubscribed	0
showbannedreason	0
showthankyou	1
showpopthankyoustats	1
popthankscount	5
mod_see_deleted	0
bbcode_img_secure	text
listcat_show_moderators	1
lightbox	1
show_list_time	720
show_session_type	2
show_session_starttime	1800
userlist_allowed	1
userlist_count_users	1
enable_threaded_layouts	0
category_subscriptions	post
topic_subscriptions	every
pubprofile	1
thankyou_max	10
email_recipient_count	0
email_recipient_privacy	bcc
captcha_post_limit	0
image_upload	registered
file_upload	registered
topic_layout	flat
time_to_create_page	1
show_imgfiles_manage_profile	1
hold_newusers_posts	0
hold_guest_posts	0
attachment_limit	8
pickup_category	0
article_display	intro
send_emails	1
fallback_english	1
cache	1
cache_time	60
iptracking	1
rss_feedburner_url
autolink	1
access_component	1
statslink_allowed	1
superadmin_userlist	0
legacy_urls	1
attachment_protection	0
categoryicons	1
avatarresizemethod	1
avatarcrop	0
user_report	1
searchtime	365
teaser	0
ebay_language	0
allow_change_subject	1
max_links	6
read_only	0
ratingenabled	0
url_subject_topic	0
log_moderation	0
attach_start	0
attach_end	14
attachment_utf8	1
autoembedsoundcloud	1
emailheader	media/kunena/email/hero-wide.png
user_status	1
signature	1
personal	1
social	1
plain_email	0
moderator_permdelete	0
avatartypes	gif, jpeg, jpg, png
smartlinking	0
defaultavatar	nophoto.png
defaultavatarsmall	s_nophoto.png
quickreply	1
avataredit	0
activemenuitem
mainmenu_id
home_id
index_id
moderators_id
topiclist_id
misc_id
profile_id
search_id
avatar_type	1
sef_redirect	1
allow_edit_poll	1
use_system_emails	0
autoembedinstagram	1

| Kunena integration settings:

Warning: Spoiler!

Kunena - Finder Disabled
Kunena - AltaUserPoints Disabled
Kunena - Community Builder Disabled
Kunena - Easyblog Disabled
Kunena - Easyprofile Disabled
Kunena - Easysocial Disabled
Kunena - Gravatar Disabled
Kunena - JomSocial Disabled
Kunena - Joomla Enabled: access=1 login=1
Kunena - Kunena Enabled: avatar=1 profile=1
Kunena - UddeIM Disabled

| Joomla! detailed language files installed:

Warning: Spoiler!

Joomla! languages installed:
en-GB	English (en-GB)
vi-VN	Vietnamese (Vietnam)

Third-party components: None

Third-party SEF components: None

Plugins: None

Modules: None

Please enable the debug mode (Kunena configuration (tab General), then the error message should be more exact.

Hi Rich,
You mean I should enable debug, and then recreate the long post to get the 500 error?
And come to back end to copy the report?
Thanks

Yes, that I meant.

Database collation check: ✔ The collation of your table fields are correct

Joomla! SEF: Enabled | Joomla! SEF rewrite: Disabled | FTP layer: Disabled |

This message contains confidential information

htaccess: Exists | PHP environment: Max execution time: 90 seconds | Max execution memory: 64M | Max file upload: 64M

Kunena menu details:

Warning: Spoiler!

ID	Name	Menutype	Link	Path	In trash
143	Forum	kunenamenu	view=home&defaultmenu=145	forum	No
144	Index	kunenamenu	view=category&layout=list	forum/index	No
145	Recent Topics	kunenamenu	view=topics&mode=replies	forum/recent	No
146	Unread	kunenamenu	view=topics&layout=unread	forum/unread	No
147	New Topic	kunenamenu	view=topic&layout=create	forum/newtopic	No
148	No Replies	kunenamenu	view=topics&mode=noreplies	forum/noreplies	No
149	My Topics	kunenamenu	view=topics&layout=user&mode=default	forum/mylatest	No
150	Profile	kunenamenu	view=user	forum/profile	No
151	Help	kunenamenu	view=misc	forum/help	No
152	Search	kunenamenu	view=search	forum/search	No
153	Diễn Đàn	mainmenu	view=home&defaultmenu=143	dien-dan	No

Joomla default template details : yootheme | author: YOOtheme | version: 1.17.0 | creationdate: December 2018

Kunena default template details : NTS KTrend | author: Nice Theme Store | version: 1.0.4 | creationdate: 2019-03-02

Kunena template params:

Warning: Spoiler!

DefaultCategoryicon
profileIconset	default
DefaultIconset	default
editorIconset	default
bootstrap	1
icomoon	1
tooltips	1
borderless	1
SubjectLengthMessage	80
fullactions	1
quick	0
displayMenu	1
displayDropdownMenu	1
displayDropdownContent	1
displayModule	1
displayBreadcrumb	1
displayAnnouncement	1
displayFooter	1
avatarPosition	left
avatarType	none
labels	0
whoisonlineName	default
formRecover	0
topicicontype	fa
fontawesome	1
socialshare	0
socialsharetag
socialtheme	classic
optional_username	0
writeaccess	0
localstorage	0
primaryColor	#007bff
forumLinkcolor	#007bff
forumLinkHoverColor	#007bff
inactiveTabcolor	#6c757d
hoverTabcolor	#007bff
activeTabcolor	#007bff
btnBgColor	#dee2e6
btnColor	#495057
btnModBg	#7e57c2
btnModColor	#ffffff
forumHeadercolor	#6c757d
forumHeaderHovercolor	#007bff
categoryIconColor	#6c757d
announcementBoxbgcolor	#fff3e0
announcementColor	#5c5c5c
enableSkinner	0
editor	0
video	1
maps	1
emoticons	1
twitter	1
ebay	1
link	1
picture	1
hide	1
spoiler	1
table	1
code	1
quote	1
divider	1
instagram	1
soundcloud	1
confidential	1
hr	1
listitem	1
supscript	1
subscript	1
numericlist	1
bulletedlist	1
alignright	1
alignleft	1
center	1
underline	1
italic	1
bold	1
strikethrough	1
colors	1
size	1
wysibb	bold,italic,underline,strike,sup,sub,justifyleft,justifycenter,justifyright,|,img,video,link,|,bullist,numlist,|,fontcolor,fontsize,fontfamily,|,quote,code,table,removeFormat
avatarSizeX	40
avatarSizeY	90
avatarSizeXThumb	36
avatarSizeYThumb	36
avatarSizeXWelcome	72
avatarSizeYWelcome	72
avatarSizeXList	36
avatarSizeYList	36
avatarSizeXPost	144
avatarSizeYPost	144
avatarSizeXProfile	200
avatarSizeYProfile	200
templatebyText
templatebyName
templatebyLink

Kunena version detailed: Kunena 5.1.10.1 | 2019-03-04 [ Janus ]
| Kunena detailed configuration:

Warning: Spoiler!

Kunena config settings:
board_offline	0
enablerss	1
threads_per_page	20
messages_per_page	6
messages_per_page_search	15
showhistory	1
historylimit	6
shownew	1
disemoticons	0
template	nts_ktrend
showannouncement	1
avataroncat	0
catimagepath	category_images
showchildcaticon	1
rtewidth	450
rteheight	300
enableforumjump	1
reportmsg	1
username	1
askemail	0
showemail	0
showuserstats	1
showkarma	1
useredit	1
useredittime	0
useredittimegrace	600
editmarkup	1
allowsubscriptions	1
subscriptionschecked	1
allowfavorites	1
maxsubject	50
maxsig	300
regonly	0
pubwrite	0
floodprotection	30
mailmod	0
mailadmin	0
captcha	0
mailfull	1
allowavatarupload	1
allowavatargallery	1
avatarquality	75
avatarsize	2048
imageheight	800
imagewidth	800
imagesize	150
filetypes	txt,rtf,pdf,zip,tar.gz,tgz,tar.bz2
filesize	32000
showranking	1
rankimages	1
userlist_rows	30
userlist_online	1
userlist_avatar	1
userlist_posts	1
userlist_karma	1
userlist_email	0
userlist_joindate	1
userlist_lastvisitdate	1
userlist_userhits	1
latestcategory	0
showstats	1
showwhoisonline	1
showgenstats	1
showpopuserstats	1
popusercount	5
showpopsubjectstats	1
popsubjectcount	5
showspoilertag	1
showvideotag	1
showebaytag	1
trimlongurls	1
trimlongurlsfront	40
trimlongurlsback	20
autoembedyoutube	1
autoembedebay	1
ebaylanguagecode	en-us
sessiontimeout	1800
highlightcode	0
rss_type	topic
rss_timelimit	month
rss_limit	100
rss_included_categories
rss_excluded_categories
rss_specification	rss2.0
rss_allow_html	1
rss_author_format	name
rss_author_in_title	1
rss_word_count	0
rss_old_titles	1
rss_cache	900
defaultpage	recent
default_sort	asc
sef	1
showimgforguest	1
showfileforguest	1
pollnboptions	4
pollallowvoteone	1
pollenabled	1
poppollscount	5
showpoppollstats	1
polltimebtvotes	00:15:00
pollnbvotesbyuser	100
pollresultsuserslist	1
allow_user_edit_poll	0
maxpersotext	50
ordering_system	mesid
post_dateformat	ago
post_dateformat_hover	datetime
hide_ip	1
imagetypes	jpg,jpeg,gif,png
checkmimetypes	1
imagemimetypes	image/jpeg,image/jpg,image/gif,image/png
imagequality	50
thumbheight	32
thumbwidth	32
hideuserprofileinfo	put_empty
boxghostmessage	0
userdeletetmessage	0
latestcategory_in	1
topicicons	1
debug	1
catsautosubscribed	0
showbannedreason	0
showthankyou	1
showpopthankyoustats	1
popthankscount	5
mod_see_deleted	0
bbcode_img_secure	text
listcat_show_moderators	1
lightbox	1
show_list_time	720
show_session_type	2
show_session_starttime	1800
userlist_allowed	1
userlist_count_users	1
enable_threaded_layouts	0
category_subscriptions	post
topic_subscriptions	every
pubprofile	1
thankyou_max	10
email_recipient_count	0
email_recipient_privacy	bcc
captcha_post_limit	0
image_upload	registered
file_upload	registered
topic_layout	flat
time_to_create_page	1
show_imgfiles_manage_profile	1
hold_newusers_posts	0
hold_guest_posts	0
attachment_limit	8
pickup_category	0
article_display	intro
send_emails	1
fallback_english	1
cache	1
cache_time	60
iptracking	1
rss_feedburner_url
autolink	1
access_component	1
statslink_allowed	1
superadmin_userlist	0
legacy_urls	1
attachment_protection	0
categoryicons	1
avatarresizemethod	1
avatarcrop	0
user_report	1
searchtime	365
teaser	0
ebay_language	0
allow_change_subject	1
max_links	6
read_only	0
ratingenabled	0
url_subject_topic	0
log_moderation	0
attach_start	0
attach_end	14
attachment_utf8	1
autoembedsoundcloud	1
emailheader	media/kunena/email/hero-wide.png
user_status	1
signature	1
personal	1
social	1
plain_email	0
moderator_permdelete	0
avatartypes	gif, jpeg, jpg, png
smartlinking	0
defaultavatar	nophoto.png
defaultavatarsmall	s_nophoto.png
quickreply	1
avataredit	0
activemenuitem
mainmenu_id
home_id
index_id
moderators_id
topiclist_id
misc_id
profile_id
search_id
avatar_type	1
sef_redirect	1
allow_edit_poll	1
use_system_emails	0
autoembedinstagram	1

| Kunena integration settings:

Warning: Spoiler!

Kunena - Finder Disabled
Kunena - AltaUserPoints Disabled
Kunena - Community Builder Disabled
Kunena - Easyblog Disabled
Kunena - Easyprofile Disabled
Kunena - Easysocial Disabled
Kunena - Gravatar Disabled
Kunena - JomSocial Disabled
Kunena - Joomla Enabled: access=1 login=1
Kunena - Kunena Enabled: avatar=1 profile=1
Kunena - UddeIM Disabled

| Joomla! detailed language files installed:

Warning: Spoiler!

Joomla! languages installed:
en-GB	English (en-GB)
vi-VN	Vietnamese (Vietnam)

Third-party components: None

Third-party SEF components: None

Plugins: None

Modules: None

I'm sorry, it was a misunderstanding. I meant, you should copy and paste the error message.
And test it please, whether the error also with the Kunena default template Crypsis exists.