I'm having trouble looking for solution on this error. I tried Googling them but some sites appears having this error as well.

I am using Joomla 3.1.5 with Simple Image Gallery Installed (plg_jw_sig-v3.0_j1.5-3.x.zip) and an error is displaying:

Notice: Undefined index: REQUEST_URI in C:\sites\premium19\abecomm\webroot\awb\cms\plugins\content\jw_sig\jw_sig.php on line 287

Here is where it appears:

antipoloweddingbelles.ph/awb/cms/index.php?option=com_k2&view=item&id=2:san-francisco-s-ruby-hill-bridal-faire&Itemid=484

I don't know how to fix. Is there any alternative besides turning off error notifications? Please help. Thanks in advance!

This is a notice and not an actual error. It will not affect your site's functionality.
In production mode you should disable error reporting.

Hello, I have a similar error | Notice: Undefined variable: defaultImagePath in I: \ xampp \ htdocs \ fotoclub3b \ plugins \ content \ jw_sig \ jw_sig.php on line 129 | all works well, I have to disable error reporting in joomla?

Hello,

As @krikor posted above, this is a warning and doesn't affect the gallery's functionality. Just Disable error reporting.