This is my test project for which I am trying a transient simulation: [https://easyeda\.com/editor\#id=\|0aba11fae8a34a039ccdb860076db290](https://easyeda.com/editor#id=|0aba11fae8a34a039ccdb860076db290) I used these settings:   Max Timestep: 10u, Stop time: 4m, StartTime: 0 And got the following errors can anybody help me with finding what causes this please : Circuit: gooduntitled Doing analysis at TEMP = 27.000000 and TNOM = 27.000000 Warning: v1: no DC value, transient time 0 value used Warning: singular matrix:  check nodes gnd and gnd Note: Starting dynamic gmin stepping Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Warning: singular matrix:  check nodes gnd and gnd Warning: Dynamic gmin stepping failed Note: Starting source stepping Warning: singular matrix:  check nodes gnd and gnd Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful gmin step Note: One successful source step Warning: singular matrix:  check nodes gnd and gnd Warning: singular matrix:  check nodes gnd and gnd Warning: source stepping failed Transient solution failed - Last Node Voltages \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\- Node                                   Last Voltage        Previous Iter \-\-\-\-                                   \-\-\-\-\-\-\-\-\-\-\-\-        \-\-\-\-\-\-\-\-\-\-\-\-\- input                                             0                    0 output                                            0                    0 r4_1                                              0                    0 q2_3                                              0                    0 vcc                                               0                    0 c3_2                                              0                    0 r1_1                                              0                    0 c3_1                                              0                    0 c1_2                                              0                    0 gnd                                               0                    0 v1#branch                                         0                    0 doAnalyses: iteration limit reached tran simulation(s) aborted Error(parse.c--checkvalid): input: no such vector. ngspice-26 done