I seem to be getting this error message all of a sudden on one of my web apps:

[HttpException (0x80004005): Unable to validate data.]
System.Web.Configuration.MachineKey.GetDecodedData (Byte[] buf, Byte[]
modifier, Int32 start, Int32 length, Int32& dataLength) +195
System.Web.UI.LosFormatter.Deserialize(String input) +60

[HttpException (0x80004005): Authentication of viewstate failed. 1) If this
is a cluster, edit <machineKeyconfiguration so all servers use the same
validationKey and validation algorithm. AutoGenerate cannot be used in a
cluster. 2) Viewstate can only be posted back to the same page. 3) The
viewstate for this page might be corrupted.]
System.Web.UI.LosFormatter.Deserialize(String input) +117
System.Web.UI.Page.LoadPageStateFromPersistenceMed ium() +102

[HttpException (0x80004005): Invalid_Viewstate


And it goes on to explain about the page. On one development machine this
works and then on mine this doesn't. Any ideas why this would suddenly start
happening?

Hi Giles,
There are 2 things you need to make sure of.
1 . If these machines are part of a webfarm make sure all web.config
validationKey,
decryptionKey have the same value across all machines.
2. All objects you place in viewstate are serializable.

Thanks,
Aris

"Giles Papworth" wrote:

I seem to be getting this error message all of a sudden on one of my web apps:
>
[HttpException (0x80004005): Unable to validate data.]
System.Web.Configuration.MachineKey.GetDecodedData (Byte[] buf, Byte[]
modifier, Int32 start, Int32 length, Int32& dataLength) +195
System.Web.UI.LosFormatter.Deserialize(String input) +60
>
[HttpException (0x80004005): Authentication of viewstate failed. 1) If this
is a cluster, edit <machineKeyconfiguration so all servers use the same
validationKey and validation algorithm. AutoGenerate cannot be used in a
cluster. 2) Viewstate can only be posted back to the same page. 3) The
viewstate for this page might be corrupted.]
System.Web.UI.LosFormatter.Deserialize(String input) +117
System.Web.UI.Page.LoadPageStateFromPersistenceMed ium() +102
>
[HttpException (0x80004005): Invalid_Viewstate
>
>
And it goes on to explain about the page. On one development machine this
works and then on mine this doesn't. Any ideas why this would suddenly start
happening?

Hi Aris,

These machines are definatly not part of a web farm and the objects are
definatly serializable.
I have changed my machine config to make sure that isn't causing the problem
however if i do that, the viewstate problem goes away and another appears.
Strangly enough it is only this one web app. All the others seem to work fine.

"Aris Houbavlis" wrote:

Hi Giles,
There are 2 things you need to make sure of.
1 . If these machines are part of a webfarm make sure all web.config
validationKey,
decryptionKey have the same value across all machines.
2. All objects you place in viewstate are serializable.
>
Thanks,
Aris
>
"Giles Papworth" wrote:
>

Also i have now changed my machine key and that seems to have resolved that
problem but now the session seems to be ending everytime i have posted data
to another page.

"Aris Houbavlis" wrote:

Hi Giles,
There are 2 things you need to make sure of.
1 . If these machines are part of a webfarm make sure all web.config
validationKey,
decryptionKey have the same value across all machines.
2. All objects you place in viewstate are serializable.
>
Thanks,
Aris
>
"Giles Papworth" wrote:
>

Hi Giles,
Try adding this in your web.config
<pages buffer="true" enableSessionState="true" enableViewState="true"
enableViewStateMac="false" />

Aris

"Giles Papworth" wrote:

Also i have now changed my machine key and that seems to have resolved that
problem but now the session seems to be ending everytime i have posted data
to another page.
>
"Aris Houbavlis" wrote:
>

What section in the web.config does that go in?

"Aris Houbavlis" wrote:

Hi Giles,
Try adding this in your web.config
<pages buffer="true" enableSessionState="true" enableViewState="true"
enableViewStateMac="false" />
>
Aris
>
"Giles Papworth" wrote:
>

<configuration>
<system.web>
<pages buffer="true" ...
...
...
...
...
</system.web>
</configuration>


"Giles Papworth" wrote:

What section in the web.config does that go in?
>
"Aris Houbavlis" wrote:
>

Thanks for that but it seems to have made no difference.

"Aris Houbavlis" wrote:

<configuration>
<system.web>
<pages buffer="true" ...
...
...
...
...
</system.web>
</configuration>
>
>
"Giles Papworth" wrote:
>

what state server setting do u have?
InProc,
SqlServer,
StateServer,
Off (Disables session state)

<system.web>
<sessionState mode="StateServer"
stateConnectionString="tcpip=SampleStateServer:424 24"
cookieless="false"
timeout="20"/>
....
....
....
</system.web

"Giles Papworth" wrote:

Thanks for that but it seems to have made no difference.
>
"Aris Houbavlis" wrote:
>

<sessionState mode="InProc" stateConnectionString="tcpip=127.0.0.1:42424"
sqlConnectionString="data source=127.0.0.1;Trusted_Connection=yes"
cookieless="false" timeout="20"/>

"Aris Houbavlis" wrote:

what state server setting do u have?
InProc,
SqlServer,
StateServer,
Off (Disables session state)
>
<system.web>
<sessionState mode="StateServer"
stateConnectionString="tcpip=SampleStateServer:424 24"
cookieless="false"
timeout="20"/>
....
....
....
</system.web
>
"Giles Papworth" wrote:
>

Hi Giles,
Any info in the event viewer?
Could be that the IIS is recycling, for some odd reason.
I would try to set session to STATESERVER.
Look here for ref:
http://msdn2.microsoft.com/en-us/lib...z9(vs.80).aspx
See if it resolves the Session problem u are experiencing.

Aris

"Giles Papworth" wrote:

<sessionState mode="InProc" stateConnectionString="tcpip=127.0.0.1:42424"
sqlConnectionString="data source=127.0.0.1;Trusted_Connection=yes"
cookieless="false" timeout="20"/>
>
"Aris Houbavlis" wrote:
>

I will add that in and see if it does the job.

"Aris Houbavlis" wrote:

Hi Giles,
Any info in the event viewer?
Could be that the IIS is recycling, for some odd reason.
I would try to set session to STATESERVER.
Look here for ref:
http://msdn2.microsoft.com/en-us/lib...z9(vs.80).aspx
See if it resolves the Session problem u are experiencing.
>
Aris
>
"Giles Papworth" wrote:
>