"Cannot open source device" error

[verdeandrea]

Hello girls and guys,

i moved a PW project to a new server and now i get this error: 
Uncaught Exception: Cannot open source device in .../wire/core/Session.php:267 

I updated PW to the last stable version 3.0.98 but i still get the same error. The site is working on localhost and on another server, so i suspect can be something related to the server settings or php.

Here is the full error 

Error: Uncaught Exception: Cannot open source device in .../wire/core/Session.php:267
Stack trace:
#0 .../wire/core/Session.php(267): session_start()
#1 .../wire/core/Wire.php(380): ProcessWire\Session->___init()
#2 .../wire/core/WireHooks.php(723): ProcessWire\Wire->_callMethod('___init', Array)
#3 .../wire/core/Wire.php(442): ProcessWire\WireHooks->runHooks(Object(ProcessWire\Session), 'init', Array)
#4 .../wire/core/Session.php(166): ProcessWire\Wire->__call('init', Array)
#5 .../wire/core/ProcessWire.php(432): ProcessWire\Session->__construct(Object(ProcessWire\ProcessWire))
#6 .../wire/core/ProcessWire.php(209): ProcessWire\ProcessWire->load(Object(ProcessWire\Config))
#7 .../index.php(52): Pr (line 267 of .../wire/core/Session.php) 

This error message was shown because: site is in debug mode. ($config->debug = true; => /site/config.php). Error has been logged.

I'm printing phpinfo hoping that can help.

Any idea on how to solve this?

Thanks

[verdeandrea]

Sorry, i think i posted this in the wrong section...

[PWaddict]

When you moved the files on the server did you also moved the folders cache, logs & sessions from site/assets/ ? If yes then I suggest you to DELETE those folders. This could be the problem.

[BitPoet]

6 hours ago, verdeandrea said:

i moved a PW project to a new server and now i get this error: 
Uncaught Exception: Cannot open source device in .../wire/core/Session.php:267 

This error is caused by PHP being unable to reach a source of randomness to generate random numbers (like, in this case, session IDs). The exact cause can vary, ranging from missing read access to /dev/urandom (check if it is included in php.ini's open_basedir if that restriction is configured) over too old PHP versions to improperly set up chroot jails (e.g. missing to include /dev/urandom) and probably some scenarios I can't think of off the top of my head.

[verdeandrea]

6 hours ago, PWaddict said:

When you moved the files on the server did you also moved the folders cache, logs & sessions from site/assets/ ? If yes then I suggest you to DELETE those folders. This could be the problem.

Thanks @PWaddict, yes i already did that, but it didn't help

Thanks @BitPoet. The PHP version is 7.1.10, so a very recent one. And from phpinfo, for open_basedir i can read 

open_basedir

no value

no value

Should i ask my server admins to change something? Thank you.

[BitPoet]

8 hours ago, verdeandrea said:

Should i ask my server admins to change something?

Contacting them about the problem is never a bad idea. Even if it's something you can change yourself, they'll likely be able to give you pointers where to look.

[PWaddict]

Try to install a fresh copy of PW to the server you have the issue and during installation PW will let you know if your server is properly configured.