Issue with Unserialize() after banner change

Hi after changing some banners in my web site i have the following error

Notice: unserialize(): Error at offset 138 of 65535 bytes in /public_html/catalog/model/extension/module.php on line 7

What can cause the error - wrong name or something else ?

Can someone help me please ?

Thanks.

That means the banner you've saved had too much data attached to it. You should change the column type from TEXT to MEDIUMTEXT on this tables/columns:

"module" table, "setting" column
"setting table, "value" column

You'll also probably need to manually delete that banner from the database, and recreate it. The banner should be in the "module" table for OpenCart 2.x/3.x, and the "setting" table for OpenCart 1.5.x.