win10 fails to connect to mysql but the same binary+dll's work on win7

Seb Tur

Hi
I have created binaries using qt 5.9.8 with mingw and mysql support. All works fine on test win7 dev and win7 test machines (blank system)
I have the exe and the whole set of required dll on a pendrive to test it on different machines.
All works on win 7 , it even work in windows emulation called WINE in Linux but it fails in win10 x32 and x64
What is strange is that db.open() returns true but when I execute a query I get an error "MySQL server has gone away"

I have disabled any firewall on win10 and on the the same win10 machines i'm ableto login to this mysql server from mysql cmd line.

any hints where to look for?

I tried building mysql plugin with different libmysql.dll versions - from mysql server and from mysql connector. the same result.

Seb Tur

Found a bug - using QT_DEBUG_PLUGINS helped here.

for some reason qt on win10 reads text files in a different way or sql treads db.setHostName parameter in a different way

so when I have a txt file .myconfig with 2 lines
db_host
db_name

for example
192.168.0.9
my_db

and code
File file(QDir::homePath()+"/.myconfig");
if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
{
qDebug()<<" konf not open";
return;
}
QString sql_host;
QTextStream in(&file);
sql_host = in.readLine();
db_name = in.readLine();

db.setHostName(sql_host);
db.setDatabaseName(db_name);

db.setUserName("user");
db.setPassword(as+as);
bool ok = db.open();

it was giving ok=true but failing on queries

fix was to use:
sql_host = in.readLine().trimmed();
intead of
sql_host = in.readLine();

so readLine() was adding space at the end in win10 (.myconfig file edited in notepad)

hope this helpes somebody else.