An HTTP error 500 occurred. /batch?id=113&op=do

First I thought my problem is similar to #635700: Installed, Connected, But Not Indexing and reported there, but error reported there is different than my Drupal installation produces. So reposting it as a separate issue.

I have checked - everything is installed properly. I have functioning multisite core, the other sites have been indexed with no issues, but on just one particular website indexing always stops at the same point - when it reaches 10%. It at firs gives:

Indexing
Solr indexing has encountered an error.
Please continue to the error page

An HTTP error 500 occurred. /batch?id=76&op=do

and when I go to the error page it displays:

910 items successfully processed. An error occurred while processing apachesolr_batch_index_nodes with arguments :apachesolr_batch_index_nodes
The search index is generated by running cron. 10% of the site content has been sent to the server. There are 7702 items left to send.

Number of documents in index: 920

Number of terms in index: 132834

Number of fields in index: 60

Field name	Index type	Distinct terms
body	text	69225
changed	date	918
comment_count	integer	26
created	date	911
entity	string	1
hash	string	1
id	string	920
im_vid_1	integer	10
im_vid_10	integer	3
im_vid_2	integer	7
im_vid_4	integer	19
im_vid_7	integer	2
im_vid_8	integer	2
im_vid_9	integer	6
is_upload_count	integer	4
language	string	1
last_comment_or_change	date	918
moderate	boolean	2
name	text	142
nid	integer	920
path	string	920
path_alias	text	1892
promote	boolean	2
site	string	1
sm_vid_География_документа	string	7
sm_vid_Медиа	string	19
sm_vid_Новостные_рассылки	string	2
sm_vid_Работа	string	2
sm_vid_Рубрики	string	3
sm_vid_Статьи	string	6
sm_vid_Форумы	string	10
sname	string	78
sort_name	sortString	78
sort_title	sortString	917
spell	textSpell	43616
status	boolean	1
sticky	boolean	1
tags_a	text	1547
tags_h2_h3	text	1815
tags_h4_h5_h6	text	14
tags_inline	text	2589
taxonomy_names	text	67
teaser	text	Not indexed
tid	integer	49
timestamp	date	912
title	text	3147
tnid	integer	1
translate	boolean	1
ts_vid_10_names	text	3
ts_vid_1_names	text	21
ts_vid_2_names	text	7
ts_vid_4_names	text	26
ts_vid_7_names	text	3
ts_vid_8_names	text	5
ts_vid_9_names	text	6
type	string	13
type_name	string	10
uid	integer	78
url	string	920
vid	integer	7