[horde] elusive missing first character and blank page problem

[Per olof Ljungmark]

Hi,

This problem has plagued us now for nearly half a year and this time I'm 
determined to nail it down. If someone reading this has even a remote 
idea of how I should take it further PLEASE let me know.

I have looked at bugs.horde.org and did not find anything that matches 
the below.

All software versions are latest stable just now but problem is seen 
through several OS and Apache/PHP/Horde upgrades.


At random, an action inside Horde, it could be a mailbox refresh, 
compose a message, open the address book or whatever, the user is 
presented with a blank page. So, it works most of the time but not every 
time and it is getting worse as well. Happens with both cache activated 
and not activated.

This will be seen in the Apache access log as a 500 error.

Switched logging to E_ALL:

Warning: include_once(Horde/Cache/one.php) [function.include-once]: 
failed to open stream: No such file or directory in 
/usr/local/www/horde/lib/Horde/Cache.php on line 174

Warning: include_once() [function.include]: Failed opening 
'Horde/Cache/one.php' for inclusion
             ^^^^^
(include_path='/usr/local/www/horde/lib:/usr/local/share/pear:.') in 
/usr/local/www/horde/lib/Horde/Cache.php on line 174

Fatal error: Call to undefined method PEAR_Error::get() in 
/usr/local/www/horde/lib/Horde/Perms/sql.php on line 270

What part of Horde is calling "Horde/Cache/one.php"? It does look like 
this call is the one that misses the first character.


Just to see what happened, I copied the Horde cache files to identical 
ones less the first letter, none.php -> one.php etc.
If I change the cache to for example memcache the error will be 
identical in behaviour but read "'Horde/Cache/emcache.php' instead

Then there is still the blank page but the missing first character 
problem is not logged, only the last line:

PHP Fatal error:  Call to undefined method PEAR_Error::get() in 
/usr/local/www/horde/lib/Horde/Perms/sql.php on line 270

This is the only line that is logged.

horde.log (at debug level) only says

Jul 05 21:24:15 HORDE [debug] [imp] Max memory usage: 2359296 bytes [pid 
10772 on line 339 of "/usr/local/www/horde/lib/Horde/Registry.php"]


ANY hints greatly appriciated!

--
per