The Metabase Could Not Be Read

​​​​​​Metabase Could Not Be Read

Error Example:

There's multiple variations on this error, but the basic error text is:

An error occurred while executing connection '<ConnectionName>': The metabase could not be read due to the following error: ​<errorReason>.

These are the known variations of the "errorReason", though this guide generally applies to all new and unknown variations as well:

• Attempting to deserialize an empty stream.
• Binary Stream '0' does not contain a valid BinaryHeader. Possible causes are invalid stream or object version change between serialization and deserialization.
• Multiple types found matching type name 'Layer2.Common.Interfaces.IFileReference'
• Unable to cast object of type '<dataType>' to '<dataType>'.
• End of Stream encountered before parsing was completed.
• Layer2.Common.CorruptedMetabaseException
• The input stream is not a valid binary format. The starting contents (in bytes) are: 00-00-C4-34-3C-3F-78-6D-6C-20-76-65-72-73-69-6F-6E ...
• Cannot find column 'x'.
• Byte array for GUID must be exactly 16 bytes long.
• Root element is missing.
• Unable to read beyond the end of the stream.
• Object reference not set to an instance of an object.
• Constructor on type 'System.TimeZoneInfo' not found.
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Cause:

There are a couple of different reasons for the base error of "The Metabase Could Not be Read":

• Errors or system disruptions during a Metabase write (re: system crashes, service crashes, unexpected reboots, server freezes) causes the metabase to become corrupted​.
• Specifically for "Attempting to deserialize an empty stream", the Metabase file will be 0 bytes in size as the writing process was interrupted before it could create the content for the file.
• Improper installation of Cloud Connector, usually multiple installations (Multiple types found matching type name 'Layer2.Common.Interfaces.IFileReference'​)
• The primary key was changed from one data type to another incompatible one (Unable to cast object of type ''<dataType> to '<dataType>'.) This specific error may also be caused by multiple installations and is a common issue with updating from non-7.8 versions to 7.8+ if the older version wasn't uninstalled first.
• The new serializer is not backward compatible with earlier Metabases (The input stream is not a valid binary format). This is due to having installed version 6.4.6.0​+, run a sync, and then trying to revert back to a prior version.

Resolution/Workaround:​

Most Metabase corruption errors can be solved by deleting and rebuilding the Metabase, but some are linked to other issues with the product and have special instructions to address them.

First, check below to see if the specific error has special instructions. If not, then follow the directions under General Resolution: Delete the Metabase.

General Resolution: Delete the Metabase

For most errors, the only way to fix the corruption is to delete the Metabase. To do this, you need to go to the Metabase folder (usually here: C:\ProgramData\Layer2 Cloud Connector\Metabase) and either delete or move the .metabase file with the same name as the connection with the error. On the next run, it will act like a new connection and start from the beginning, rebuilding a fresh Metabase file.

Please note that:

For Uni-directional Syncs: You will likely need to enable Overwrite Destination as now there is pre-existing content in the target. If the primary keys are set correctly, it should just update the items in the target. If not, then it will do a full delete/reinsert.

For Bi-directional Syncs: You will likely get Conflict errors now as both sides may have different modified dates. To get around this easily, you can set the Conflict Resolution to WinnerLoser for a single run, so that the conflicts are handled automatically, then you can switch it back to your normal method. DO NOT use KeepBoth in this situation as you will get hundreds of false CONFLICT files that you will have to delete manually.

Multiple Types Found Matching Type Name 'Layer2.Common.Interfaces.IFileReference

You need to uninstall all versions of the Cloud Connector from the host machine using the "Clean Install" steps. This error is very common with updating from a non-7.8 version to a 7.8+ version if you did not uninstall the prior version first. The clean install usually fixes it, but if not, you may need to completely remove the application from the machine (all related files, all assembly references, all registry entries) and then re-install fresh.