---------- release buiild - no issues noticed provided *.cfg is copied as well
- Followed https://dev.mysql.com/doc/refman/8.0/en/innodb-table-import.html

rm -rf 107517/
bin/mysqld --no-defaults --initialize-insecure --basedir=$PWD --datadir=$PWD/107517 --log-error-verbosity=3
bin/mysqld_safe --no-defaults --basedir=$PWD --datadir=$PWD/107517 --core-file --socket=/tmp/mysql.sock  --port=3306 --log-error=$PWD/107517/log.err --mysqlx-port=33330 --mysqlx-socket=/tmp/mysql_x_ushastry.sock --log-error-verbosity=3  --secure-file-priv="" --local-infile=1 2>&1 &


Session1>create table itest (id int, str1 varchar(20), index(str1) );
Query OK, 0 rows affected (0.02 sec)

Session1>insert into itest values (1, 'val1');
Query OK, 1 row affected (0.01 sec)

Session1>alter table itest add column str2 varchar(20), algorithm=INSTANT;
Query OK, 0 rows affected (0.01 sec)
Records: 0  Duplicates: 0  Warnings: 0

Session1>insert into itest values (2,'val1', 'val2');
Query OK, 1 row affected (0.00 sec)


Session2>create table itest2 like itest;
Query OK, 0 rows affected (0.02 sec)

Session2>alter table itest2 discard tablespace;
Query OK, 0 rows affected (0.00 sec)



Session1>FLUSH TABLES itest FOR EXPORT;
Query OK, 0 rows affected (0.00 sec)

Session1>

# Copy the itest.ibd file and itest.cfg metadata file to itest2.ibd and itest2.cfg

ls -l 107517/test
total 132
-rw-r----- 1 umshastr common    908 Jun 23 17:10 itest.cfg
-rw-r----- 1 umshastr common 131072 Jun 23 17:09 itest.ibd
cp 107517/test/itest.ibd 107517/test/itest2.ibd
cp 107517/test/itest.cfg 107517/test/itest2.cfg

ls -l 107517/test
total 264
-rw-r----- 1 umshastr common    908 Jun 23 17:13 itest2.cfg
-rw-r----- 1 umshastr common 131072 Jun 23 17:12 itest2.ibd
-rw-r----- 1 umshastr common    908 Jun 23 17:10 itest.cfg
-rw-r----- 1 umshastr common 131072 Jun 23 17:09 itest.ibd

--  use UNLOCK TABLES to release the locks acquired by the FLUSH TABLES ... FOR EXPORT statement

Session1>UNLOCK TABLES;
Query OK, 0 rows affected (0.00 sec)

Session1>

-- import the tablespace

Session2>alter table itest2 import tablespace;
Query OK, 0 rows affected (0.03 sec)

Session2>select * from itest2;
+------+------+------+
| id   | str1 | str2 |
+------+------+------+
|    1 | val1 | NULL |
|    2 | val1 | val2 |
+------+------+------+
2 rows in set (0.00 sec)

---------- debug build (i) No issues noticed if .cfg is copied as well for itest2 (ii) If .cfg is not copied then assert noticed as reported
- Followed https://dev.mysql.com/doc/refman/8.0/en/innodb-table-import.html

rm -rf 107517/
bin/mysqld --no-defaults --initialize-insecure --basedir=$PWD --datadir=$PWD/107517 --log-error-verbosity=3
bin/mysqld_safe --no-defaults --mysqld-version=debug --basedir=$PWD --datadir=$PWD/107517 --core-file --socket=/tmp/mysql.sock  --port=3306 --log-error=$PWD/107517/log.err --mysqlx-port=33330 --mysqlx-socket=/tmp/mysql_x_ushastry.sock --log-error-verbosity=3  --secure-file-priv="" --local-infile=1 2>&1 &

bin/mysql -uroot -S /tmp/mysql.sock --prompt='Session1>'
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 8.0.29-debug MySQL Community Server - GPL - Debug

Copyright (c) 2000, 2022, Oracle and/or its affiliates.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

Session1>create database test;
Query OK, 1 row affected (0.01 sec)

Session1>use test
Database changed
Session1>create table itest (id int, str1 varchar(20), index(str1) );
Query OK, 0 rows affected (0.07 sec)

Session1>insert into itest values (1, 'val1');
Query OK, 1 row affected (0.02 sec)

Session1>alter table itest add column str2 varchar(20), algorithm=INSTANT;
Query OK, 0 rows affected (0.06 sec)
Records: 0  Duplicates: 0  Warnings: 0

Session1>insert into itest values (2,'val1', 'val2');
Query OK, 1 row affected (0.01 sec)

Session1>

Session2>use test
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
Session2>create table itest2 like itest;
Query OK, 0 rows affected (0.07 sec)

Session2>alter table itest2 discard tablespace;
Query OK, 0 rows affected (0.02 sec)

Session2>

Session1>FLUSH TABLES itest FOR EXPORT;
Query OK, 0 rows affected (0.00 sec)

Session1>

# Copy the itest.ibd file and itest.cfg metadata file to itest2.ibd and itest2.cfg

ls -l 107517/test
ls -l 107517/test
total 132
-rw-r----- 1 umshastr common    908 Jun 23 17:23 itest.cfg
-rw-r----- 1 umshastr common 131072 Jun 23 17:22 itest.ibd

cp 107517/test/itest.ibd 107517/test/itest2.ibd
cp 107517/test/itest.cfg 107517/test/itest2.cfg

ls -l 107517/test
total 264
-rw-r----- 1 umshastr common    908 Jun 23 17:25 itest2.cfg
-rw-r----- 1 umshastr common 131072 Jun 23 17:25 itest2.ibd
-rw-r----- 1 umshastr common    908 Jun 23 17:23 itest.cfg
-rw-r----- 1 umshastr common 131072 Jun 23 17:22 itest.ibd


(i) No issues noticed if .cfg is copied as well for itest2

--  use UNLOCK TABLES to release the locks acquired by the FLUSH TABLES ... FOR EXPORT statement

Session1>UNLOCK TABLES;
Query OK, 0 rows affected (0.00 sec)

Session1>

-- import the tablespace

Session2>alter table itest2 import tablespace;
Query OK, 0 rows affected (0.06 sec)

Session2>select * from itest2;
+------+------+------+
| id   | str1 | str2 |
+------+------+------+
|    1 | val1 | NULL |
|    2 | val1 | val2 |
+------+------+------+
2 rows in set (0.00 sec)

Session2>


(ii) If .cfg is not copied then assert noticed as reported 

Session1>use test
Database changed
Session1>create table itest (id int, str1 varchar(20), index(str1) );
Query OK, 0 rows affected (0.06 sec)

Session1>insert into itest values (1, 'val1');
Query OK, 1 row affected (0.01 sec)

Session1>alter table itest add column str2 varchar(20), algorithm=INSTANT;
Query OK, 0 rows affected (0.06 sec)
Records: 0  Duplicates: 0  Warnings: 0

Session1>insert into itest values (2,'val1', 'val2');
Query OK, 1 row affected (0.01 sec)


Session2>use test
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
Session2>create table itest2 like itest;
Query OK, 0 rows affected (0.07 sec)

Session2>alter table itest2 discard tablespace;
Query OK, 0 rows affected (0.02 sec)

Session2>



Session1>
Session1>FLUSH TABLES itest FOR EXPORT;
Query OK, 0 rows affected (0.00 sec)

Session1>

# Copy the itest.ibd file to itest2.ibd(don't copy over itest.cfg)

 cp 107517/test/itest.ibd 107517/test/itest2.ibd

--  use UNLOCK TABLES to release the locks acquired by the FLUSH TABLES ... FOR EXPORT statement

Session1>UNLOCK TABLES;
Query OK, 0 rows affected (0.00 sec)

Session1>

-- import the tablespace - issue noticed as reported

Session2>alter table itest2 import tablespace;
ERROR 2013 (HY000): Lost connection to MySQL server during query
No connection. Trying to reconnect...
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (111)
ERROR:
Can't connect to the server

>bin/mysqld_safe: line 199: 21347 Aborted                 (core dumped) env MYSQLD_PARENT_PID=21110 nohup /export/home/tmp/ushastry/mysql-8.0.29/bin/mysqld-debug --no-defaults --basedir=/export/home/tmp/ushastry/mysql-8.0.29 -

-bt

(gdb) bt
#0  0x00007f2476eb6aa1 in pthread_kill () from /lib64/libpthread.so.0
#1  0x0000000004795d5b in my_write_core(int) ()
#2  0x00000000033e3406 in handle_fatal_signal ()
#3  <signal handler called>
#4  0x00007f24750f3387 in raise () from /lib64/libc.so.6
#5  0x00007f24750f4a78 in abort () from /lib64/libc.so.6
#6  0x00000000033e357b in my_server_abort() ()
#7  0x000000000478cfec in my_abort() ()
#8  0x0000000004c080b4 in ut_dbg_assertion_failed(char const*, char const*, unsigned long) ()
#9  0x0000000004c272d8 in rec_init_null_and_len_comp ()
#10 0x0000000004c28c3a in rec_init_offsets_comp_ordinary(unsigned char const*, bool, dict_index_t const*, unsigned long*) ()
#11 0x0000000004c27957 in rec_init_offsets_new(unsigned char const*, dict_index_t const*, unsigned long*) ()
#12 0x0000000004c284e4 in rec_init_offsets(unsigned char const*, dict_index_t const*, unsigned long*) ()
#13 0x0000000004c28753 in rec_get_offsets_func(unsigned char const*, dict_index_t const*, unsigned long*, unsigned long, ut::Location, mem_block_info_t**) ()
#14 0x0000000004ab316d in PageConverter::update_records(buf_block_t*) ()
#15 0x0000000004ab33e9 in PageConverter::update_index_page(buf_block_t*) ()
#16 0x0000000004ab383f in PageConverter::update_page(buf_block_t*, unsigned long&) ()
#17 0x0000000004ab3fd1 in PageConverter::operator()(unsigned long, buf_block_t*) ()
#18 0x0000000004e18309 in fil_iterate(Fil_page_iterator const&, buf_block_t*, PageCallback&) ()
#19 0x0000000004e190e9 in fil_tablespace_iterate(dict_table_t*, unsigned long, Compression::Type, PageCallback&) ()
#20 0x0000000004ab923d in row_import_for_mysql(dict_table_t*, dd::Table*, row_prebuilt_t*) ()
#21 0x00000000048de2a6 in ha_innobase::discard_or_import_tablespace(bool, dd::Table*) ()
#22 0x000000000357c5e8 in handler::ha_discard_or_import_tablespace(bool, dd::Table*) ()
#23 0x00000000032c2b90 in Sql_cmd_discard_import_tablespace::mysql_discard_or_import_tablespace(THD*, TABLE_LIST*) ()
#24 0x00000000038ae712 in Sql_cmd_discard_import_tablespace::execute(THD*) ()
#25 0x00000000031f5106 in mysql_execute_command(THD*, bool) ()
#26 0x00000000031f721b in dispatch_sql_command(THD*, Parser_state*) ()
#27 0x00000000031ed4c2 in dispatch_command(THD*, COM_DATA const*, enum_server_command) ()
#28 0x00000000031eb4a2 in do_command(THD*) ()
#29 0x00000000033cdc5f in handle_connection ()
#30 0x000000000501c1cb in pfs_spawn_thread ()
#31 0x00007f2476eb1ea5 in start_thread () from /lib64/libpthread.so.0
#32 0x00007f24751bbb0d in clone () from /lib64/libc.so.6
(gdb)