One of the properties of the Web Part has an incorrect format

 

 

Web Part Error:

One of the properties of the Web Part has an incorrect format.
Windows SharePoint Services cannot deserialize the Web Part.
Check the format of the properties and try again

 

I have got this error while modifying a Custom Web Part when i added to it the properties Width and/or Height. Simply I renamed it and that's all.

 

 

 

Here there is the same error on other situation.

 

 

 

Lack of permissions for application pool account can cause Web Parts to not display on home page

If the account used for authenticating the application pool for Windows SharePoint Services does not have read and write permissions to the directory that Windows uses for temporary files, Web Parts may not display properly. When this occurs, the following error message appears:

Web Part Error: One of the properties of the Web Part has an incorrect format. Windows SharePoint Services cannot deserialize the Web Part. Check the format of the properties and try again.

1. Locate the system temporary directory.
   1. Right-click My Computer, and then click Properties.
   2. On the Advanced tab, click Environment Variables.
   3. In the System variables list, note the directories for TEMP and TMP.
2. Go to the directories listed for TEMP and TMP.
   1. Click Start, and then click Run.
   2. Type the path to folder that contains the folder associated with TEMP and/or TMP, and then click OK.
3. Right-click on the folder for the temporary directory, and then click Sharing and Security.
4. On the Security tab, verify that the application pool account for the content virtual server has Read and Write permissions in each of the directories.

For information about configuring the application pool account, see the Windows SharePoint Services Administrator's Guide.