When I upgraded to PHP 4.3.9 on this server I would occasionally get an error that didn’t make any sense. The two that I saw were:

Parse error: parse error, unexpected T_VARIABLE in (filename) on line 10
Warning: Unexpected character in input: ‘ (filename) on line 20

The line numbers didn’t have anything that I can see that are wrong with them, and they varied across different files.

Some related links I found during my research:

PHP bug 5448
PHP bug 14141
PHP bug 24864
PHP bug 30241
PHP bugs search
Computing news
Redhat bugzilla
Sitepoint

The problem seems to happen when I’m working on a file and making changes to it, then reload the page in the browser. So far it’s a complete mystery. I restarted the server and wasn’t able to reproduce it right away, but that doesn’t mean it’s resolved.

The server is a dual-CPU machine, and the 4.2.3 changelog says, “Fixed several bugs in the multithreaded version that could cause random parse errors, especially on machines with multiple CPUs.” I wonder if the bugs were reintroduced in later versions.

I got the following error:

Warning: Unexpected character in input: ‘ in (filename) on line 163

On line 163 I had the following:

echo isset( $search_email )

and towards the end of the page I got the following error:

Fatal error: Call to undefined function: sset() in (filename)on line 163

My guess is that the letter i in isset was somehow construed to be invalid when the file was parsed and as a result it tried to find the sset method instead of the isset method. After a reload, everything worked fine so the PHP code is syntactically correct.

I just found a test that seemed to work pretty well. I had a foreach block and when I put an @ symbol in front of the foreach, it threw a parse error at first (which is correct) but when I removed it on versions 4.3.9, 4.3.8 and 4.3.6 it produced one more error, then another reload cleared the error. This behavior no longer occurred when I downgraded to 4.3.4. I would put the @ symbol in and it would give the parse error (a different error too by the way) and then when I removed it from the file and reloaded, it worked fine.