SQL Error 1055

[Midori]

I have SQL Error 1055 , just in index.php another pages are OK.
   

[.m.]

do you have a plugin / modification which displays attachments on index page ?
if so disable that plugin / remove the modification until someone provides fix.

[Matt]

The quickest way would be to disable MySQL strict mode.

You also need to upgrade your forum, by the styling of that error message you're on either 1.4.x or 1.6.x which is unsupported.

[Midori]

Thanks dear .m.
I try the quickest way first and If no works I try your solution . But how can to disable MySQL strict mode , dear Matt I dont know? Do you guide me?

[Omar G.]

Thanks dear .m.
I try the quickest way first and If no works I try your solution . But how can to disable MySQL strict mode , dear Matt I dont know? Do you guide me?

Read the following threads, carefully.
https://community.mybb.com/thread-221300.html
https://community.mybb.com/thread-221056.html

[Midori]

Omar G, Matt, .m., dears
My forum does not work much and I have not been active for about a year. I did not have this problem, and I do not know why and how it was created. Anyway thank you for your help . I'm trying to get it right, but if do not, I must stop it . Thanks again. I am waiting for suggestions for simpler ways.

[Serpius]

The quickest way would be to disable MySQL strict mode.

In my case, my hosting provider will NOT disable MySQL Strict mode. I am on a shared hosting plan.

They are attempting to force me to switch to VPS or dedicated server with a monthly service charge that will be very expensive for me.

Are there other options to fix this issue?

[Omar G.]

Are there other options to fix this issue?

Move away from them to another host provider.

[Serpius]

Are there other options to fix this issue?

Move away from them to another host provider.

Sorry, that is not possible. 

I have pre-paid for my hosting plan and I will lose a lot of money if I make a switch. So, I can't do it. 

[Omar G.]

You should check if their claim is true then, regarding their inability to proceed with your request. I'm in a shared cheap hosting and I don't have this issue. I didn't know forcing MySQL Strict Mode was enforceable for host providers. Sounds unreasonable if you ask me.