Please use the instructions in the FAQ:How do I manually upload data from USB Mass Storage devices to Garmin Connect? to manually upload the activities to your account. Delete the Edge from Express then add it back again. Create some new activities and see if they will transfer. Make sure you use the Lap/Reset button after each activity.
The most common causes of that error are bad or corrupt data on the Edge which a Master Reset will fix, or the Time, Date & Time Zone on the computer is not correct for its location. Please double check your computers Time, Date & Time Zone and Master Reset the Edge then try again. If you continue to have trouble, send me the Express Logs.
Open Express 1. Click the gear icon in the upper right corner 2. Send Logs to Garmin 3. Enter in the characters V2NY7 (only good once) 4. Click Submit