Missing transaction

[Beerwizzard]

Hey guys! I've got a problem.
Some days ago I've recieved a transaction but now it is not visible in my electrum wallet (and it seem like I'm also not able to use this coins). Due to the blockchain.info my satoshies are still on the same address but this transaction is simply not displayed for me. Currently using 2.8.3 version of Electrum on my Windows 7. How can I fix that issue?
I've tried to install 3.0 version but I'm getting a python error so it seems like I have to wait for some updates (as it was already menioned in other threads).

[pooya87]

first make sure your transaction does belong to you and also is not spent.
you can use this https://blockchain.info/unspent?active=$address (replace $address with your bitcoin address) to see if the transaction is unspent. you may have spent it without knowing.

if you were 100% sure of the two things above then it may be some issue with Electrum, try restarting Electrum, change servers and make sure you are connected. it should be fixed like this but as final solution you can (make a backup from your seed and wallet file first) create a new wallet from your seed and let it sync. you don't have to delete the old wallet either, just make a new wallet and call it some other name.

[Beerwizzard]

Thanks mate! Problem solved now.  I only had to change the server and restart Electrum afterwads. The solution was simple.
Anyway such issue can be pretty cruel: the transaction just disappeared (no inputs and no outputs in the wallet while the tx is unspent) from the wallet while everything else worked perfectly fine so it could be easy to simply lose it in my own wallet. 

[pooya87]

Thanks mate! Problem solved now.  I only had to change the server and restart Electrum afterwads. The solution was simple.
Anyway such issue can be pretty cruel: the transaction just disappeared (no inputs and no outputs in the wallet while the tx is unspent) from the wallet while everything else worked perfectly fine so it could be easy to simply lose it in my own wallet. 

your welcome.
that is the issue with using an SPV wallet. you are trusting a third party to give you the transactions that belong to you. that third party can be malicious or simply slower or on an orphaned chain or lots of other things and give you bad information.
the good news is that it can not give you transactions that doesn't belong to you since you have the block headers and you receive the full tx and it has to be correctly signed.
but it can withhold transactions that belong to you and you will have no way of knowing it with just having the block headers.

https://en.bitcoin.it/wiki/Thin_Client_Security
https://gist.github.com/justusranvier/451616fa4697b5f25f60