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However I am trying to run SQL request in SQL tab I receive 502 error, but same query in SEARCH tab works fine.

I was using php-7.2 and phpmyadmin-5.0.2 when error appeared for the first time.

I've read a lot of posts that issue happens due to low post_max_size value . I updated it to post_max_size = 50000M in my php.ini. Update of php/phpmyadmin also doesn't help .

For now versions are PHP 7.4.15 phpmyadmin-5.0.4

502 error

Search tab

And some another strange thing there, Webserver returns 400 code [info] 29#29: *246923 recv() failed (104: Connection reset by peer) while reading client request headers,

Артем Черемісін
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1 Answers1

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HTTP status 502 means connection issue between client (whatever it is PHP or SQL client) and database instance. You have to check if access between APP and DB is feasible.

There might be lot of problems durring connection, for example:

  • No direct connection between APP & DB
  • DB has firewall setup that deny connection on port 3306
  • You are running DB in container but port 3306 isn't exposed in your docker-compose.yml file
  • APP & DB are running in corporate network which is protected with proxy server (squid for example)

To diagnose basic issues telnet is your tool of choise. With it you can simulate/check connection between app server and db on specific port and see if connection can be established. Telnet will also tell you some usefull information.

# telnet <DB_SERVER> 3306
Trying <DB_SERVER>
telnet: connect to address <DB_SERVER>: Connection refused
Facty
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