What version of phpBB are you using? phpBB 3.0.7
What is your board's URL? No answer given
Who do you host your board with? Company server
How did you install your board? I used the download package from phpBB.com
Is your board a fresh install or a conversion? Update from a previous version of phpBB3
Do you have any MODs installed? Yes
Is registration required to reproduce this issue? No
What version of phpBB3 did you update from? phpBB 3.0.2
What MODs do you have installed? Topic View Tracker
What styles do you currently have installed? Prosilver
What language(s) is your board currently using? EN
Which database type/version are you using? Oracle
What is your level of experience? New to PHP and phpBB
When did your problem begin? After upgrading from 3.0.2 to 3.0.7.
Please describe your problem. This is a test instance that's copied from our production board, separate database but identical setup. After upgrading to anything past 3.0.5 (ie 3.0.6 or 3.0.7), will get ORA-01756: quoted string not properly terminated  error.
I can bypass the error by editing phpBB3/styles/prosilver/template/overall_header.html, remove the space in front of " 'height=225,resi....." in the line that says window.open(url.replace(/&/g, '&'), '_phpbbprivmsg', 'height=225,resizable=yes,scrollbars=yes, width=400');.
Then, the next error will occur whenever I try to post, w/ error ORA-01704: string literal too long .
This seems like a CLOB problem, anything larger than 4000 character isn't getting inserted on this particular page.
Error detail see attached image.