2960x & 2960s stacking?

Question

Hey guys recently I tried to introduce a 2960x switch into a 2960s stack.
I prepped the bpth switches and made sure the prefer sdm was set to default as well as setting the stack port speed on the 2960s stack to 10 so its would be compatible.
Once i stacked the switches i got a version mismatch error and an auto upgrade message, after waiting roughly 40 minutes with no succcessful upgrade i removed the X switch from the stack
below are the IOS running on both switches
*    1 52    WS-C2960S-48FPS-L  15.0(2)SE5            C2960S-UNIVERSALK9-M
     2 28    WS-C2960S-24TD-L   15.0(2)SE5            C2960S-UNIVERSALK9-M
3 52    WS-C2960X-48FPD-L  15.0(2)EX4            C2960X-UNIVERSALK9-M
Any thoughts on how to successfully stacked these?? Thanks in advance

Answer 1

  Hi,
some info about stacking different switch 2960S with 2960X.
More info is available at:
http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-2960-x-series-switches/white_paper_c11-728327.html
Hope this can help you.
Mixed Stacks: FlexStack and FlexStack-Plus
The 2960-S and 2960-X support a mixed stack of 2960 models. All  these 2960 models run the FlexStack protocol, allowing them to be  stacked together into a single stack. The exception is the 2960-XR does  not stack with either the 2960-X or the 2960-S. The 2960-XR has the  IP-Lite feature set, and this is not compatible with the LAN Base  feature set on the 2960-X and 2960-XR. Table 2 shows all the allowed  mixed stack combinations. What is crucial is the Cisco IOS Software  feature set. All 2960 models with the LAN Base Cisco IOS Software  feature set can stack together.
Table 2. Allowed Mixed Stack Combinations
Mixed Stack Combination
2960-XR IP Lite
2960-X LAN Base
2960-S LAN Base
2960-XR IP Lite
Yes
No
No
2960-X LAN Base
No
Yes
Yes
2960-S LAN Base
No
Yes
Yes
Table 3 shows FlexStack-Plus backward compatibility and performance of 2960-X and 2960-XR with the 2960-S switches.
Table 3. Backward Compatibility
Scale of Mixed Stack Combination
Max Stack Bandwidth
Stack Limit
Cisco IOS Software Feature Set
2960-XR IP Lite
80Gbps
8
IP Lite
2960-X LAN Base
80Gbps
8
LAN Base
2960-X, 2960-S LAN Base
40Gbps
4
LAN Base
When the 2960-S and 2960-X members are stacked together, the entire  stack (even the 2960-X members) fall back to FlexStack capabilities.  Mixing 2960 members limits the max stack members to four, and 20Gbps  stack bandwidth per member, and 40Gbps per stack.