PYRO - Errors and Troubleshooting

Pyro Manual

10. Errors and Troubleshooting

The Pyro Errors section describes the various errors that can occur when using Pyro. It only describes Pyro's custom exceptions - other Python exceptions may occur due to other runtime problems.

The Troubleshooting section provides various hints and tips when you can't get things to work as expected.

Pyro Errors

Pyro Exception Hierarchy

Exception
- PyroError
  - URIError
  - DaemonError
  - NamingError
  - NoModuleError
  - ProtocolError
    - ConnectionClosedError
      - TimeoutError
    - ConnectionDeniedError

Initialization

OSError-- is raised when Pyro can't create or open the storage directory specified by PYRO_STORAGE.

Name Server

NamingError-- The Name Server responds with the following kinds of NamingError exceptions (raised by the remote NS object):

Error string	raised by	description
name already exists	register	The name you're trying to register is already present in the NS database
name not found	unregister	You're trying to unregister an unknown name.
name not found	resolve	The name you're trying to resolve is unknown by the NS.
invalid name	various methods	The object name is invalid. It must be a string with no whitespaces and only 7-bit ASCII characters.
invalid URI	various methods	The object URI that was passed is invalid.
parent is no group	register	A new name can only be registered within a group. The name is not in a correct group.
attempt to resolve groupname	resolve	A resolve was done on a group name, only object names can be resolved.
group not found	various methods	The name contains an unknown group.
is no group	deleteGroup, list	An operation was done that can only be performed on a group, not on an object name.
(parent)group not found	various methods	The name contains an unknown (parent) group.
name is not absolute	nearly all methods	Object names have to be absolute (i.e. fully specified in the namespace).
default group name is not absolute	nearly all methods	The default group name has to be absolute (i.e. fully specified in the namespace).

PyroError-- The NameServerLocator raises PyroError "Name Server not responding" if it failed to discover the Name Server (via the getNS method).

Also, the PYROAdapter raises NoModuleError "No module named XYZ" if it cannot import a Python module. See below in the table.

Also, the startup code in configuration.py raises PyroError "Error reading config file" if Pyro's configuration file cannot be read.

Pyro Core

URIError-- The PyroURI object raises URIError "illegal URI format" when you try to create a PyroURI object from an illegal URI. Also "unknown host" means that you supplied an unknown hostname or IP address for the URI.

DaemonError-- The Daemon object raises DaemonError "Couldn't start Pyro daemon" if it was unable to start. This usually means that the required network port (socket) is temporarily unavailable because another Pyro daemon is already running on it.

PYRO Protocol adapter

Various exceptions may be raised by the PYRO protocol code:

Exception	Error string	raised by	description
`ConnectionClosedError`	connection lost	receive code	The network connection was lost while receiving data.
`ConnectionClosedError`	connection lost	send code	The network connection was lost while sending data.
`ProtocolError`	incompatible protocol in URI	`bindToURI` method of `PYROAdapter`	You supplied an incompatible protocol ID. Use 'PYRO'.
`ProtocolError`	connection failed	`bindToURI` method of `PYROAdapter`	Network problems caused the connection to fail. Also the Pyro server may have crashed.
`ProtocolError`	invalid header	receive code	A message with an invalid header has been received.
`ProtocolError`	incompatible version	receive code	A message from an incompatible Pyro version has been received.
`ProtocolError`	unsupported protocol	`getProtocolAdapter`	You tried to get a protocol adapter for an unsupported protocol. Currently only the 'PYRO' protocol is supported.
`ProtocolError`	compression not supported	receive code	An incoming message used compression, which this Pyro setup doesn't support (most likely you don't have the `zlib` module).
`ProtocolError`	unknown object ID	receive code	Incoming method call for an unknown object (i.e. the object ID was not found in the Daemon's list of active objects).
`NoModuleError`	No module named XYZ	remote method call code	The Pyro server cannot import the Python module XYZ that contains the code for an object that was passed in a remote call. If you don't use mobile code, the Pyro server must have all `.py` files available.
`PyroError`	attempt to supply code denied	remote method call code	Either a client tried to submit code to a server that hasn't enabled mobile code, or the server had enabled mobile code but the codeValidator refused to accept it.
`ConnectionDeniedError`	unspecified reason	`bindToURI` method of `PYROAdapter`	No specific reason given for denying the connection
`ConnectionDeniedError`	server too busy	`bindToURI` method of `PYROAdapter`	The Pyro server has too many connections at this time so your request for another connection was denied.
`ConnectionDeniedError`	host blocked	`bindToURI` method of `PYROAdapter`	The server blocks your host/IP address.
`ConnectionDeniedError`	security reasons	`bindToURI` method of `PYROAdapter`	General security issue prevented a connection.
`TimeoutError`	connection timeout	while transferring data in PyroAdapter	The communication took longer that the timeout perioud that was specified. (default: off)

Util

KeyError-- The ArgParser will raise KeyError "no such option" if you try to getOpt an option that has not been detected in the option string and you have not supplied a default value to getOpt (otherwise that default value is returned).

Troubleshooting

Problem	Possible cause	Hint/tip
The Name Server or my own Pyro server refuses to start, aborts with `DaemonError`	The daemon can't set up the network port (socket), probably because another daemon is already running, or another process occupies the resource.	Wait a little while and try again (sometimes it takes a while for resources to become available again). If this doesn't work, find the other daemon that is probably running and shut it down, or specify another port for the new daemon. Sorry, but your new process can't yet use the daemon of another running process - perhaps in a future Pyro version.
Name Server acts weird with names or groups	not using built-in static NS proxy	always use the `Pyro.naming.NameServerProxy` returned by the Name Server Locator.
Pyro refuses to initialize, aborts with `IOError` and/or things saying 'permission denied' or similar	You probably specified a wrong location for Pyro's storage directory and/or logfiles. Perhaps you don't have permission to write in those locations.	Fix those locations by changing the configuration items. Make sure you have permission to write to those locations. Usually `PYRO_STORAGE` must be changed to point to a correct directory.
My code can't find the Name Server, it aborts with "Name Server not responding"	The Pyro Name Server is not running or it can't be discovered automatically. The latter may be the case if your network doesn't support broadcasts or if the NS is running on a different subnet that cannot be reached by a broadcast.	Start the NS if it's not running. If the problem persists, you have to help the `NameServerLocator` by specifying the host and perhaps even the port number where the NS is running. You can also try to obtain the NS' URI string and create a proxy directly from this string, bypassing the `NameServerLocator`.
'name not absolute' errors after changing default namespace group.	The default group name for the `PYRO_NS_DEFAULTGROUP` config item must be an absolute name (starting with the root char).	Change it to an absolute name.
Client can't bind to URI or find URI in Name Server. NS is running ok, server is running ok.	The URI is not registered correctly in the Name Server.	Make sure that the client accesses the correct Name Server (the one that the server used to register the object), especially if you're running multiple NS. Also make sure that the client uses the correct URI.
Client problems when accessing Pyro object attributes, client prints stuff like `<bound method DynamicProxy.__invokePYRO__ of DynamicProxy ... >` instead of attribute value	You are using regular dynamic proxy	Use attribute enabled proxy, either a static one generated by `pyroc` or the dynamic one, see `getAttrProxyForURI`.
Client crashes with "No module named ..." or similar when accessing attributes	The attribute object is an instance of a class that cannot be found/imported on the client	make the module that contains every attribute class available on the client, or write getters.
Pyro doesn't use my configuration settings!	Other settings overrule your settings.	Check if there is an environment variable that overrules your config file, or perhaps even a setting in your code..
Pyro object doesn't initialise correctly	Pyro objects cannot have a remote __init__ method	Use explicit remote initialization by using a custom init method..
My proxy acts very weird after I updated the Pyro object	Using old static proxy	Regenerate static proxy (or use dynamic proxy).
General network errors when using firewall or multiple network adapters (can't find NS, Pyro uses wrong IP address in URIs)	Firewalls need special treatment	Read the chapter Features and Guidelines, topic "DNS, IP addresses and firewalls".
Client cannot connect anymore after restarting the server	Pyro URIs change every time the server is restarted, and the client uses an old URI	update the URI on the client, or use the Name Server, or use Persistent Naming.
Deadlock (Pyro freezes)	Callback waits for other object (occurs in 'conversation')	Consider using Oneway invocations or the Event Server.
Pyro Object created on server and returned to client doesn't work	You are probably not returning a proxy but the object itself.	Return a proxy instead: `return Obj.getAttrProxy()`
Other problem not mentioned here	Your code probably breaks a Pyro rule	read the Features and Guidelines chapter, topic "Usage rules and guidelines"
SSL problems	?	Sorry, I don't know much about SSL. Ask on Usenet or the mailing list.
Pyro crashes.	Most likely a bug.	Contact me.

Pyro Manual